How to warm up email accounts in Instantly 2026: exact settings, score interpretation, and week-by-week timelines

Last updated: June 2026 · Sarah Okonkwo, Sales ops specialist, deliverability obsessive

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TL;DR — 5 things to know before reading

• Email warmup is the technical prerequisite for inbox placement; a new inbox that skips warmup will land in spam regardless of message quality, subject line, or audience targeting — warmup cannot be bypassed
• Instantly's warmup network automates the process: once enabled, it sends warmup emails between accounts in the network, generates engagement (replies, not-spam signals), and builds sender reputation before cold outreach begins
• The exact warmup timeline by use case: 2 weeks for low-volume testing (under 30 sends/day), 3–4 weeks for standard cold email (30–50/day), 6–8 weeks for higher-volume operations, 8–12 weeks for maximum long-term deliverability per Instantly's cold email benchmarks
• Instantly's warmup score is a composite metric — scores above 80 indicate readiness for low volume, above 90 for standard volume; a score below 70 means the inbox must not be used for cold campaigns; score interpretation and exact thresholds are covered in full in this guide
• Verdict: warmup is not optional and cannot be compressed; Instantly automates it; Inframail provides the dedicated inboxes; Quarvio delivers the verified contacts; Aimfox runs LinkedIn outreach from the same data in parallel

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Our take

Email deliverability management is where outbound programs succeed or fail, and warmup is the foundation of deliverability management. The practitioners who get 35%+ open rates and 10%+ reply rates consistently are not the ones with the cleverest subject lines — they are the ones who take warmup seriously, who never rush the timeline, and who continue warmup maintenance after campaigns launch rather than treating warmup as a one-time step.

The mechanism behind warmup is specific and worth understanding precisely. Email providers (Gmail, Outlook, Yahoo) evaluate every sender based on their sending history: volume patterns, engagement rates, and complaint rates. A new inbox with no history is an unknown entity. When an unknown inbox sends 50 cold emails on day one, it presents every risk signal email providers watch for — sudden volume spike from an unknown sender. The result is predictable: spam folder routing, which produces zero open rates.

Warmup builds the sending history that email providers use to classify a sender as legitimate. Instantly's warmup network does this systematically: it sends small volumes of warmup emails from each inbox to other inboxes in the network, those receiving inboxes engage positively (open, reply, move from spam to inbox, mark as not-spam), and the sending inbox accumulates a positive reputation signal. By the time cold outreach begins, the inbox has an established history of sent email with positive engagement — which is exactly the profile that email providers route to inbox. Inframail provides the dedicated Microsoft 365 inboxes on separate domains that warmup operates on, keeping cold email reputation completely isolated from primary business email. Quarvio provides the verified contact data that campaigns send to once warmup is complete. Aimfox handles LinkedIn outreach to the same prospects in parallel.

What email warmup does: the technical mechanism

When a new email inbox is created and connected to a sending platform like Instantly, its reputation with major inbox providers is essentially neutral — no history, no signals to evaluate. Email providers use multiple signals to determine whether an incoming email should be delivered to inbox, promotions tab, or spam:

Domain age: How old is the sending domain? Very new domains (under 30 days) are treated with additional scrutiny. This is why purchasing cold email domains in advance — 30–60 days before you need them — is a common practice among experienced cold email operators.

Sending volume history: Is the volume from this inbox gradual or sudden? A sudden spike from 0 to 50 emails per day is a pattern associated with spam operations. Gradual increase over weeks is associated with legitimate business senders.

Engagement signals: Are recipients opening emails from this inbox? Are they replying? Are they moving emails to inbox if they land in spam? Are they marking emails as spam? High open rates and reply rates signal legitimate correspondence. High spam-marking rates signal unwanted email.

Technical authentication: Are SPF, DKIM, and DMARC records correctly configured? Missing or misconfigured authentication records are associated with forged-sender spam. Per Mailgun's email authentication guide, correct DMARC configuration is the technical baseline that all legitimate high-volume senders maintain.

Warmup addresses the first three of these factors. Technical authentication (the fourth) is handled by Inframail automatically through its DNS configuration.

Prerequisites before starting warmup

Before enabling warmup in Instantly, confirm these prerequisites are complete:

DNS records verified:

• SPF record: confirms which servers are authorised to send email for the domain
• DKIM record: cryptographic signature that verifies email authenticity
• DMARC record: policy that instructs receiving providers what to do with emails that fail SPF/DKIM checks

For Inframail inboxes, all three are configured automatically. Verify they show as confirmed in the Inframail dashboard before proceeding. For any inbox not provisioned through Inframail, manually verify DNS records using a DNS lookup tool.

Inbox type confirmed: Use Microsoft 365 inboxes (via Inframail) rather than Gmail or custom SMTP where possible. Microsoft 365 inboxes have high baseline deliverability because enterprise companies use the same infrastructure, giving new inboxes a deliverability starting point that pure SMTP connections do not have.

Inbox credentials confirmed: Verify you can log into each inbox at webmail.office.com before connecting to Instantly. An inbox you cannot manually access is an inbox with an unknown configuration state.

Step 1: Connect the inbox to Instantly

1. In Instantly, navigate to Email Accounts → Add Account
2. Select Microsoft 365 / Outlook as the connection type
3. Authenticate via OAuth (recommended) or enter credentials manually
4. Confirm each inbox shows “Connected” status in the Email Accounts list
5. Repeat for every inbox you plan to warm

Sub-step verification: After connecting, navigate to each inbox and send a test email to an external address. Confirm receipt in inbox (not spam). If the test email lands in spam: the domain has a pre-existing reputation issue or DNS is misconfigured. Investigate before starting warmup — warmup cannot repair a domain that is already blacklisted.

Benchmark: A freshly provisioned Inframail inbox should pass this test email check. If it fails, submit a support request to Inframail before proceeding.

Failure mode: Connecting inboxes and immediately enabling warmup without test-sending first. A misconfigured inbox generates warmup emails that fail authentication, which produces negative warmup signals (not-delivered, marked as spam at receiving inboxes) rather than positive ones — actively harming reputation rather than building it.

Step 2: Configure warmup settings for each inbox

In Instantly, navigate to each connected email account and open the Warmup tab. Configure every setting explicitly rather than accepting defaults.

2a: Core warmup settings reference

2b: Why reply rate at 35% matters

The warmup network exchanges emails between Instantly accounts. The reply rate setting tells Instantly's network to reply to approximately 35% of warmup emails received from your inbox. Replies are one of the strongest positive engagement signals for email providers — if recipients are replying to emails from this inbox, it is clearly not spam.

Setting reply rate below 20% produces a weaker engagement signal. Setting it above 50% is not realistic and may be detected as artificial. 30–40% is the standard range used by practitioners optimising for warmup efficiency.

2c: Why 7-day warmup schedule matters

Running warmup 7 days per week (including Saturday and Sunday) produces a faster reputation build than 5 days per week for the same elapsed calendar time. Warmup during weekends does not disadvantage deliverability — email providers receive warmup emails from Instantly's network and engage with them positively regardless of day of week. The total positive engagement signals accumulated in 2 weeks at 7-day warmup equals approximately 2.8 weeks at 5-day warmup.

For teams that want to reach campaign-ready status faster without compromising warmup quality, 7-day warmup is the correct configuration.

Step 3: Understanding and interpreting warmup scores

Instantly's warmup score is a composite metric displayed per inbox in the Email Accounts section. Understanding what each score range means for inbox placement determines when you can safely launch campaigns.

3a: Score interpretation guide

Important: The warmup score is an internal Instantly metric, not a direct measurement from Gmail or Outlook. A high warmup score means the warmup network process is working correctly — warmup emails are being sent, received, opened, and replied to at the expected rates. High warmup score correlates strongly with good inbox placement but is not a guarantee.

The external validation is the test email check: send a test email from the warmed inbox to a personal Gmail address and confirm it lands in inbox. Do this test at week 2, week 3, and before any campaign launch.

3b: Score volatility and what it means

The warmup score fluctuates day to day by 3–5 points. This is normal. What to watch for:

Normal fluctuation: Score moves ±5 points day to day while maintaining an upward overall trend. This is expected warmup behaviour.

Score plateau: Score reaches 60–70 and stops increasing over 5+ days. This indicates the warmup process is running but not generating sufficient positive engagement. Common causes: DNS record issue causing warmup emails to fail authentication at some receiving inboxes.

Score drop: Score decreases by 10+ points in a single day. This is a signal of a problem: warmup emails are being marked as spam at receiving inboxes, or a blacklist has been applied to the sending domain. Investigate immediately.

Score collapse: Score drops from 80+ to below 50 in 2–3 days after campaign launch. This is the most common score problem. The campaign send volume was too high for the inbox's warmup state, and the additional sending created volume anomaly signals that overrode the warmup reputation. Fix: pause campaign sends immediately, reduce volume significantly when restarting, extend warmup period by 2 weeks.

Step 4: The week-by-week warmup timeline

This is the most Instantly-specific section of this guide. The exact settings and progression by week for a standard 3–4 week warmup to campaign-ready state.

Week 1: Foundation phase

Warmup configuration for week 1:

What is happening: The inbox is establishing its first sending history. Warmup emails are being sent and received in the Instantly network. Email providers are beginning to accumulate data on this sender.

Action if score is below 20 at end of week 1: Check DNS records. Check MXToolbox blacklist status for the sending domain. Verify warmup is actually sending (check “warmup emails sent today” counter). Contact Inframail support if the domain is newly provisioned.

Week 2: Building phase

Warmup configuration for week 2:

What is happening: Positive engagement history is accumulating. The inbox has now sent 80–120 warmup emails over two weeks with 35% reply rate — approximately 30–40 replies received. Email providers are building a sender model for this inbox.

Test at end of week 2: Send a test email to a personal Gmail. If it lands in inbox: promising. If it lands in spam: either warmup is not working effectively or DNS has an issue. Review warmup settings and DNS before continuing.

Action if score is below 45 at end of week 2: Same diagnosis as week 1. DNS and blacklist checks first, then warmup settings review.

Week 3: Maturation phase

Warmup configuration for week 3:

What is happening: The inbox has 3 weeks of gradual sending history with positive engagement. Reputation is established for low-to-moderate volume. A test campaign to 30–50 contacts is appropriate at this stage if score is above 70.

Important configuration change for week 3: When launching a test campaign alongside warmup, reduce the campaign daily limit per inbox to 15–20 (lower than the ultimate target). The inbox is now sending warmup emails plus campaign emails — ensure the combined total does not exceed 40 per day.

Week 4: Ready state

Warmup configuration for week 4:

What is happening: The inbox is fully warmed for standard campaign volume. The warmup network is running at near-maximum daily volume. Campaign sends of 30–40 per day are appropriate alongside maintained warmup.

Post-week 4 maintenance: Continue warmup indefinitely. Do not disable warmup when campaigns launch. The ongoing warmup signal (daily positive engagement from the network) is what maintains inbox placement during active cold campaigns. Disabling warmup when campaigns start is one of the most common causes of gradual deliverability degradation over time.

Extended warmup: weeks 5–12

For operations running at higher volumes (40–80 emails per inbox per day), per Instantly's cold email benchmarks, extending warmup to 8–12 weeks before reaching maximum send volume produces inbox placement rates above 95% for properly configured sending domains.

The extended warmup schedule: continue incrementing campaign send volume by 5 emails per inbox per week from week 4 onward until reaching your target. Do not jump from 30 to 80 per day in one step. Each increment should run for 1 week before the next.

Step 5: Monitor warmup health signals during the warmup period

During the warmup phase, monitor these signals on a 2-day cycle:

5a: In Instantly dashboard

Navigate to Email Accounts and check:

• Warmup score per inbox (should trend upward week over week)
• Warmup emails sent today (should be incrementing with the daily ramp)
• Any inbox-level warning flags (yellow or red indicators)

5b: External signals — MXToolbox blacklist

Check MXToolbox blacklist checker for each sending domain weekly during warmup. Enter the sending domain name and verify it is not listed on any major blacklist.

If the domain appears on a blacklist during warmup: pause warmup and all activity immediately. Submit delisting requests via the blacklist operator's removal process. Do not resume warmup until the domain is confirmed delisted. Continuing warmup on a blacklisted domain generates negative signals (warmup emails being rejected) rather than positive ones.

5c: Google Postmaster Tools

For domains sending to Gmail addresses, connect them to Google Postmaster Tools. This provides:

• Domain reputation (High / Medium / Low / Bad)
• Spam rate (percentage of received emails marked as spam)
• Delivery errors rate

During warmup, domain reputation will typically show “Low” initially and progress to “Medium” and eventually “High” as the warmup period progresses. A domain that remains at “Low” or drops to “Bad” after 3 weeks of warmup has a DNS or blacklist issue that must be resolved.

Benchmark target: Domain reputation should reach “Medium” or higher by the end of week 3. Reaching “High” by week 4–6 is achievable with correct configuration and verified contact data from Quarvio.

Step 6: When to launch campaigns — readiness criteria

Launch campaigns when all of the following criteria are met, not just one or two:

All six criteria must pass before launching. A warmup score of 85 with a blacklisted domain means the warmup score is not reflecting the actual inbox state. Check all criteria independently.

Soft launch protocol

Do not launch at full campaign volume on day one of campaign activation:

This graduated launch ensures that if there is a deliverability issue at campaign volume, it is detected at small scale before affecting the entire contact list.

Step 7: Maintain deliverability after campaigns launch

Warmup is not a one-time setup step. It is an ongoing maintenance process that runs in parallel with cold campaigns.

7a: Keep warmup enabled permanently

After campaign launch, keep warmup enabled on all connected inboxes. Instantly manages warmup and campaign sends from the same inbox simultaneously. The warmup network continues sending warmup emails throughout the day alongside campaign emails, maintaining the positive engagement signal that inbox placement depends on.

Disabling warmup after campaigns launch is one of the most common causes of gradual deliverability degradation over 30–60 days.

7b: Monthly deliverability maintenance checklist

7c: Per-campaign list quality verification

Before importing each new contact list, verify source quality. Per Google's email sender guidelines, spam complaint rates above 0.3% cause emails to be filtered across all Gmail recipients. Bounce rates above 2% are a strong negative signal.

Using verified contact data from Quarvio with a 90% deliverability guarantee keeps bounce rates below 3% and spam complaint rates near zero — which is the most significant single factor in maintaining inbox placement over time.

Step 8: Recovering a damaged inbox

When warmup score drops significantly or campaign deliverability deteriorates, follow this recovery protocol:

8a: Diagnosis sequence

1. Pause all campaign sends immediately (do not pause warmup)
2. Run MXToolbox blacklist check for the sending domain
3. Check Google Postmaster domain reputation
4. Check Instantly warmup score and warmup email volume (is warmup still sending?)
5. Review recent campaign bounce rates and complaint signals in Instantly

8b: Recovery actions by diagnosis

Blacklisted domain: Submit delisting requests to each blacklist. While delisting is pending, move all campaign sends to a different domain. Do not resume campaigns on the blacklisted domain until confirmed delisted.

Score dropped due to over-sending: Reduce campaign sends to 10–15 per inbox per day. Continue warmup at current settings. Wait 2 weeks. Resume campaign volume at a lower starting point with a 5 per inbox per week increment.

Score dropped due to poor list quality (high bounce rate): The bounce rate damaged the inbox's engagement ratio. Stop importing contacts from the same source. Clean the existing list by removing bounced addresses. Wait 2 weeks at low volume before resuming.

Score dropped for unknown reason: Increase warmup reply rate to 40% temporarily. Reduce all other sends to zero for 1 week. Monitor score recovery. If score does not improve: contact Instantly support.

8c: Retiring vs. recovering an inbox

Some inboxes are more cost-effective to retire than recover. Recovery is worthwhile when:

• The domain is less than 6 months old
• The blacklisting or score drop is a single incident with identifiable cause
• The recovery timeline is under 4 weeks

Retire and replace with a new inbox when:

• The domain has been blacklisted multiple times
• Recovery has been attempted twice without lasting improvement
• The inbox is more than 12 months old and has accumulated reputation debt from multiple campaigns

Inframail makes retirement and replacement straightforward: new inboxes are provisioned within 24–48 hours.

Warmup settings complete reference

Every warmup-related setting in Instantly, with exact values and explanations:

Advanced warmup tactics

Warming multiple inboxes simultaneously

For operations that need 10+ warmed inboxes, start all inboxes in warmup at the same time rather than staggering them. Staggering means inboxes become campaign-ready at different times, creating an uneven ramp where some inboxes are driving full volume while others are still warming.

Starting all inboxes simultaneously means all are campaign-ready at the same time, allowing a clean full-volume campaign launch at the 3–4 week mark.

Monitoring at scale: When managing 10+ inboxes in warmup, check Instantly's account-level warmup overview (rather than individual inbox tabs) to get a summary view of all warmup scores simultaneously.

Domain portfolio management

Experienced cold email operators maintain a domain portfolio: some domains are actively being used in campaigns, some are warming to replace or expand, and some are retiring.

Recommended portfolio structure for teams sending 200+ emails per day:

• 5 active campaign domains (10 inboxes each, warmed)
• 3 warming domains (6 inboxes each, in 3–4 week warmup)
• 2 retiring domains (being wound down, moved to low volume)

This ensures campaign capacity is never interrupted: when a domain is retired, a warming domain takes its place.

Pre-warming domains before you need them

Purchase cold email domains 6–8 weeks before you plan to use them. Begin Inframail provisioning and Instantly warmup 4–5 weeks before the planned campaign launch. This builds an older domain (better reputation baseline) and completes warmup before the campaign deadline.

Teams that buy domains the week they need them are always behind on warmup. Plan 6–8 weeks ahead.

Reactivating dormant inboxes

An inbox that has not sent any email for 30+ days loses some of its established reputation. If reactivating a dormant inbox:

1. Re-enable warmup at 5–10 emails per day
2. Do not launch campaigns immediately
3. Run warmup for 1–2 weeks to re-establish the sending history
4. Recheck warmup score before returning to full campaign volume

A dormant inbox is not as easy to reactivate as a brand-new inbox is to warm. The domain may have aged reputation (good) but the sending history gap is a negative signal. A 2-week re-warmup is the reliable standard.

Monitoring warmup ROI by inbox

In Instantly, track warmup score progression per inbox over time. An inbox that has been warming for 4 weeks but remains below 70 is not contributing to campaign capacity and is likely consuming warmup network resources without building usable reputation.

Flag these underperforming inboxes early (by week 3 if score is below 60), diagnose the cause, and either fix or retire them rather than carrying them indefinitely.

Troubleshooting guide

Problem 1: Warmup score stuck below 60 after 3 weeks

Symptoms: Score not increasing despite warmup being enabled for 3 weeks.

Diagnosis: Warmup emails are not generating positive engagement at receiving inboxes. Most likely cause: a DNS record issue causing warmup emails to fail authentication.

Fix:

1. Check SPF, DKIM, and DMARC records on the sending domain using the Inframail dashboard
2. Confirm DMARC policy is not set to “reject” (which would reject warmup emails that fail DMARC)
3. Check that warmup emails are actually being sent — navigate to the inbox's warmup tab and confirm the daily volume counter is incrementing
4. Run MXToolbox blacklist check — if listed, delist before expecting score to improve
5. Contact Instantly support with inbox details if DNS and blacklist checks pass

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Problem 2: Warmup score drops sharply after campaign launch

Symptoms: Score was 85+ before campaign launch; drops to 60–70 within a week of launching campaigns.

Diagnosis: Campaign send volume is too high relative to the warmup state. The inbox is receiving volume anomaly signals because campaign emails added on top of warmup emails exceeded the safe daily total.

Fix:

1. Pause all campaign sends immediately (do not pause warmup)
2. Check the combined daily send total: warmup + campaign sends. If combined total exceeded 50 per day, this is the cause
3. Reduce campaign sends to 10–15 per inbox per day when restarting
4. Wait 2 weeks for warmup score to recover to 80+
5. Ramp campaign volume by 5 emails per inbox per week from the restart point

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Problem 3: Warmup emails landing in spam at test accounts

Symptoms: When sending test emails to a personal Gmail during warmup, they land in spam or promotions tab, not inbox.

Diagnosis: The inbox has not yet built sufficient reputation, or a DNS issue is causing authentication failure.

Fix:

1. Run the test email at week 3, not week 1 — it is normal for week 1–2 test emails to land in spam
2. If the test email lands in spam at week 3: check DMARC record configuration
3. Verify the test email shows SPF and DKIM “pass” in the email headers — in Gmail, click the three-dot menu on the received email and “Show original” to view authentication headers
4. If DKIM shows “fail”: the DKIM record is either missing or misconfigured. Review Inframail configuration or contact Inframail support

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Problem 4: Sending domain gets blacklisted during warmup

Symptoms: MXToolbox blacklist check shows the domain is listed on one or more blacklists during the warmup period.

Diagnosis: A newly provisioned domain was registered by a previous owner with a spam history, or domain registration flagged as suspicious.

Fix:

1. Identify which specific blacklists have listed the domain (MXToolbox shows the full list)
2. For Spamhaus: visit spamhaus.org/lookup and follow the delisting process
3. For Barracuda: visit barracudacentral.org/rbl/removal-request
4. For each blacklist: submit a removal request explaining the domain is newly provisioned for legitimate B2B outreach
5. While delisting is in process: pause warmup and all sends from this domain. Move to a different domain
6. Resume warmup only after confirmed delisted

Prevention: before starting warmup on a new domain, run a blacklist check immediately after Inframail provisioning. Catch pre-existing blacklisting before investing 3+ weeks in warmup.

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Problem 5: Warmup score is high (90+) but inbox placement is still poor

Symptoms: Warmup score shows 90+ but campaign emails are landing in spam.

Diagnosis: Warmup score reflects warmup network behaviour, not real-world inbox placement. A high warmup score does not guarantee inbox placement if the campaign messages themselves trigger spam filters.

Fix:

1. Verify with a test email: send a campaign-identical email (same subject, same body, same links) from the warmed inbox to a personal Gmail. Does it land in inbox?
2. If the test email lands in spam: the issue is message content, not inbox reputation
3. Review subject line for trigger phrases: all-caps words, excessive punctuation, financial promises
4. Review email body: remove any links (test first without links to isolate whether links are the cause)
5. Review the tracking domain: if using Instantly's shared tracking domain, switch to a custom tracking domain (the shared domain may have accumulated poor reputation from other senders)
6. Per Google's email sender guidelines, spam rate above 0.1% causes filtering — ensure earlier campaigns from this inbox had low complaint rates

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Problem 6: Two inboxes on the same domain have very different warmup scores

Symptoms: Inbox A on domain.com shows warmup score of 85; Inbox B on domain.com shows score of 55.

Diagnosis: Warmup scores in Instantly are per-inbox, not per-domain. Each inbox builds its own sending history independently. Inbox B either started warmup later or had its warmup disrupted.

Fix:

1. This is not a problem requiring a fix — it is expected behaviour when inboxes are connected at different times
2. For Inbox B: confirm warmup is enabled and check the warmup email volume counter. If lower than expected, review warmup settings
3. Do not use Inbox B in campaigns until its score reaches 80+, regardless of Inbox A's score

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Problem 7: Score drops gradually over 60 days while campaigns are active

Symptoms: Warmup score was 90 at campaign launch and has gradually dropped to 70 over 2 months.

Diagnosis: Most commonly caused by warmup being disabled after campaign launch, or by campaign emails generating enough negative signals (bounces, complaints) to erode the warmup-built reputation.

Fix:

1. Confirm warmup is still enabled — check the warmup tab for each inbox
2. Check campaign bounce rates for the past 30 days — if above 3%, the contact lists are introducing invalid addresses that are damaging reputation
3. Check complaint signals in Instantly and Google Postmaster
4. If warmup was disabled: re-enable and run at maximum warmup volume for 2 weeks before resuming full campaign sends
5. If bounce rate is the cause: review contact source quality and ensure all future imports use Quarvio verified data

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Problem 8: Warmup appears to be running but emails are not being sent

Symptoms: Warmup is enabled, settings look correct, but the “warmup emails sent today” counter shows 0 for several days.

Diagnosis: The inbox connection is not active, or Instantly is encountering an authentication error when attempting to send warmup emails.

Fix:

1. Navigate to the inbox in Email Accounts and check the connection status indicator
2. If status shows “Disconnected” or “Error”: reconnect the inbox using the Microsoft 365 OAuth flow
3. If status shows “Connected” but warmup is not sending: disconnect and reconnect the inbox, then re-enable warmup
4. If the issue persists after reconnection: contact Instantly support with the inbox ID and error details

Community evidence

Instantly reviews on G2 consistently identify warmup quality as the most cited reason practitioners choose Instantly over other cold email platforms. The built-in warmup network is a competitive differentiator — practitioners who previously used standalone warmup tools cite the simplicity of having warmup and campaign sending in the same platform.

“I manage deliverability for 12 clients. Every one of them uses Instantly warmup from Day 1, on Inframail inboxes, before any cold send goes out. The ones who have tried to skip the warmup or shorten it always come back with the same problem: 8% open rates and zero replies. The warmup is the whole game. There is no shortcut.”

— Verified G2 reviewer, cold email deliverability consultant, Instantly reviews on G2

“After 3 weeks of warmup on a new Inframail inbox, my open rates were 41% on the first campaign. The domain had zero history before Instantly warmup. The network does what it says it does — it builds real sender reputation before you need it.”

— Verified G2 reviewer, outbound sales rep, B2B SaaS, Instantly reviews on G2

“The warmup score interpretation confused me at first. I thought above 80 meant I could send at full volume immediately. Wrong. Above 80 means ready to start at low volume and ramp. I hit 85 at week 3 and launched at 15 per inbox per day, not 50. By week 6, the score was 96 and I was comfortably at 45 per day with 38% open rates.”

— Verified G2 reviewer, outbound agency founder, Instantly reviews on G2

Our actual stack

Frequently asked questions

How long does it take to warm up an email account in Instantly?

For standard cold email campaigns (30–50 emails per inbox per day): 3–4 weeks minimum. For higher-volume operations: 6–8 weeks. For maximum long-term deliverability: 8–12 weeks per Instantly's cold email benchmarks. The warmup period cannot be meaningfully compressed without sacrificing reputation quality. Teams that try to compress warmup to 1 week consistently see open rates below 20%.

Can I run cold email campaigns while warmup is still running?

Yes, but only after the initial warmup period (3 weeks minimum). Instantly manages warmup emails and campaign sends from the same inbox. Keep warmup enabled after launching campaigns — do not disable it. The ongoing warmup signal maintains positive sender reputation while cold outreach is active. Disabling warmup when campaigns start causes gradual deliverability degradation over 30–60 days.

What warmup score in Instantly indicates that an inbox is ready for cold outreach?

Score above 80: ready for low-volume campaigns (20–30 per inbox per day). Score above 90: ready for standard volume (30–50 per inbox per day). Score below 70: not ready — extend warmup by 1–2 weeks and recheck. The score is an internal Instantly metric, so also validate with a test email sent to a personal Gmail account to confirm the inbox is actually delivering to inbox and not spam.

How do I check if my warmup is actually working in Instantly?

Navigate to each email account in Instantly and open the warmup tab. Confirm: (1) warmup is enabled (not just toggled on but actually sending), (2) the daily warmup volume counter shows emails being sent, (3) the score is trending upward over 5–7 days. If warmup is toggled on but the daily volume shows 0, the inbox connection has an issue — reconnect the inbox and re-enable warmup.

Does email warmup expire if I stop using an inbox?

Yes. An inbox that stops sending entirely (both warmup and campaign sends) for more than 30 days loses some of its established reputation. Email providers update their sender models based on recent activity. For inboxes paused for 30+ days: restart warmup at 5–10 emails per day and run for 1–2 weeks before resuming campaigns. Keep warmup enabled on all inboxes even during campaign pauses to maintain the reputation signal.

What is the correct warmup configuration for a brand new Inframail inbox?

Enable: daily start volume 5–8, daily increment +2, maximum daily volume 35, reply rate 35%, warmup schedule 7 days per week, subject tag off, send window 7am–6pm. Leave warmup running for 3 weeks without launching any campaigns. Check warmup score at day 14 and day 21. Launch test campaign at day 21 if score is above 80. Scale gradually from week 4 onward.

Why did my warmup score drop after I launched a campaign?

The most common cause is combined send volume (warmup + campaign) exceeding 50 per inbox per day. Instantly's warmup network signals are diluted when campaign sends add significant additional volume on top of warmup sends. The fix: pause campaigns, continue warmup at normal settings for 2 weeks, restart campaigns at 10–15 per inbox per day, and increment by 5 per week.

How many inboxes can I warm simultaneously in one Instantly account?

Instantly does not publish a hard limit on simultaneous warmup inboxes, and practitioners regularly warm 20–50 inboxes simultaneously in a single account. The warmup network scales to accommodate multiple inboxes. The practical consideration is monitoring: managing warmup for 50 inboxes individually is time-consuming. Use the account-level warmup overview to spot underperforming inboxes rather than checking each one individually.

Can I warm up a Gmail inbox in Instantly?

Yes, Instantly can connect Gmail inboxes via OAuth. However, Gmail has strict sending limits (500 per day for standard Gmail, 2,000 for Google Workspace), and Google actively restricts automated sending behaviour. For cold email warmup, Microsoft 365 inboxes via Inframail are the recommended choice — they have higher sending limits, better baseline deliverability for cold outreach, and are provisioned on dedicated domains rather than @gmail.com addresses.

What happens if I pause warmup for a vacation or holiday?

Pausing warmup for 3–4 days has minimal impact. Pausing for more than a week causes gradual score reduction because the inbox stops accumulating positive engagement signals. If you are pausing campaign operations for more than a week, keep warmup running at its current settings. Warmup does not require active management — Instantly runs it automatically.

How do I know when to retire an inbox instead of trying to recover it?

Retire an inbox when: (1) it has been blacklisted more than twice, (2) two recovery attempts have not produced a lasting score improvement above 70, (3) the inbox is more than 18 months old and shows persistent deliverability degradation. Recovery is worthwhile for single-incident problems (one blacklisting, one score drop from over-sending). Persistent problems indicate a domain reputation issue that is more cost-effective to replace than repair.

How does inbox warmup interact with Instantly's Unibox?

Warmup emails from the Instantly network are separate from real prospect replies. Warmup emails do not appear in Unibox — Unibox shows only real campaign reply emails. There is no confusion between warmup activity and genuine prospect replies. The warmup process runs entirely in the background, and the score it generates is the only visibility you need into it via the warmup tab in each email account.

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