How to connect Inframail to Smartlead (complete setup guide)

Last updated: June 2026 · Ryan Mercer, SDR turned cold email consultant, 8 years outbound

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TL;DR — 7 things to know before reading

• Inframail inboxes connect to Smartlead via standard SMTP and IMAP credentials; Smartlead accepts any SMTP connection, making Inframail-to-Smartlead the most straightforward integration in the cold email infrastructure stack
• The critical distinction between Smartlead and Instantly for Inframail connections: Smartlead uses "email accounts" that you add one by one via SMTP/IMAP; the workflow is the same as Instantly but the interface labels and navigation differ
• Inbox rotation in Smartlead is configured at the campaign level by assigning multiple email accounts to one campaign; Smartlead automatically rotates sends across all assigned accounts
• Warmup in this stack requires a separate tool: Inframail does not have built-in warmup, and Smartlead's built-in warmup (Smartlead Warmup) must be enabled separately for each inbox; alternatively, connect inboxes to Instantly solely for warmup and to Smartlead for campaigns
• Deliverability monitoring in Smartlead focuses on bounce rates, reply rates, and spam complaint rates at the inbox and campaign level; you need to monitor these actively and pause inboxes showing degradation
• Exact SMTP settings: server smtp.office365.com, port 587, security STARTTLS; IMAP settings: server outlook.office365.com, port 993, security SSL/TLS
• Verdict: use Inframail for inbox provisioning, Smartlead for campaign sending and rotation, Instantly for warmup if Smartlead Warmup is not your preferred option, and Quarvio for verified contact data before campaigns go live; Aimfox adds the LinkedIn channel alongside email

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Our take

The Inframail-to-Smartlead connection is technically straightforward: export SMTP and IMAP credentials from Inframail, paste them into Smartlead's email account settings, send a test, and you are connected. The reason a guide for this process needs to exist is not because the technical steps are complex — they are not — but because the operational setup around the connection has real complexity that teams consistently underinvest in.

The three areas where teams make costly mistakes after completing the basic connection: inbox rotation configuration (assigning too many inboxes to one campaign without understanding how Smartlead distributes sends, leading to some inboxes over-sending and others barely used), warmup integration (connecting inboxes to Smartlead without any warmup active, or turning off warmup when campaigns begin), and deliverability monitoring (setting up the connection and launching campaigns without watching per-inbox metrics, missing early warning signs of inbox reputation degradation until significant damage has occurred).

This guide covers all three of those operational layers, not just the connection steps. The connection takes 5 minutes per inbox. Getting the rotation, warmup, and monitoring configuration right takes longer but produces a cold email setup that can sustain campaign volume without constant reputation fires. After 8 years doing outbound with different tool stacks, the practitioners who get consistent results are not the ones who set up the fastest — they are the ones who invest in the operational configuration the first time and do not have to rebuild every 60 days.

Inframail provides the Microsoft 365 inboxes. Smartlead handles campaign sequencing and sending. Instantly can handle warmup if you prefer not to use Smartlead's built-in warmup feature. Quarvio supplies the verified contacts that keep bounce rates below the threshold where inbox reputation starts compounding negatively. Aimfox runs LinkedIn outreach in parallel with the email campaigns.

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Why Inframail and Smartlead work together

Inframail's architecture is built around SMTP and IMAP credential export. When you create an inbox in Inframail, you receive: an SMTP username, an SMTP password, and the standard Microsoft 365 connection settings. These credentials are all Smartlead needs to send and receive email from that inbox.

Smartlead accepts any SMTP/IMAP connection regardless of the underlying mail provider. It does not require OAuth, does not require a specific provider integration, and does not require any custom configuration beyond the standard connection parameters. This means the Inframail-to-Smartlead connection is as simple as any SMTP connection.

The deliverability argument for this stack: Inframail inboxes run on Microsoft 365 infrastructure, which recipient spam filters treat with higher trust than shared ESP infrastructure. Smartlead's multi-inbox rotation and campaign management sits on top of that infrastructure. The combination is Microsoft 365 deliverability quality at Inframail's flat pricing with Smartlead's campaign management capabilities.

The alternative stacks that teams use for comparison: Inframail-to-Instantly (identical inbox quality, different sending tool UX), self-provisioned Microsoft 365-to-Smartlead (same quality, higher per-inbox cost), Google Workspace-to-Smartlead (slightly different deliverability characteristics, per-seat pricing). Inframail-to-Smartlead is the appropriate choice for teams that prefer Smartlead's UX and campaign management features over Instantly's while still wanting Microsoft 365 inbox quality.

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Prerequisites

Inframail inboxes provisioned with DNS verified. Before connecting to Smartlead, all Inframail inboxes must have SPF, DKIM, and DMARC passing for their sending domain. Do not connect inboxes with unverified authentication. Use MXToolbox to confirm records before proceeding.

Inframail SMTP and IMAP credentials exported. Each inbox you plan to connect to Smartlead requires its individual SMTP credentials (server, port, username, password) and IMAP credentials (server, port, username, same password). Export these from Inframail before starting the Smartlead connection process.

A Smartlead account. Sign up for Smartlead separately if you have not already. Smartlead's pricing is based on active leads in your account; review their current plan tiers at Smartlead.com before choosing a plan.

Warmed inboxes (or a warmup plan). New Inframail inboxes must be warmed before being used for cold outreach. If you are connecting freshly created inboxes, plan for a 14–28 day warmup period before campaigns begin. Smartlead has its own warmup feature; alternatively, use Instantly for warmup and Smartlead for campaign sending.

Verified contact data ready. Have your contact list validated before setup is complete. Quarvio provides pre-verified B2B contacts at $129 for 5,000 through $699 for 50,000 with a 90% deliverability guarantee.

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Step-by-step: connecting Inframail to Smartlead

Step 1: Gather Inframail credentials for all inboxes

What to do: Before opening Smartlead, collect the SMTP and IMAP credentials for every Inframail inbox you plan to connect. Having them ready before starting the Smartlead setup prevents switching back and forth.

Sub-steps:

1. Log in to Inframail and navigate to Inboxes
2. For each inbox, open the settings and note or copy: full email address, SMTP password, SMTP server (smtp.office365.com), SMTP port (587), SMTP security (STARTTLS), IMAP server (outlook.office365.com), IMAP port (993), IMAP security (SSL/TLS)
3. Use Inframail's bulk SMTP export if available — this generates a CSV with all inbox credentials that you can use as a reference during Smartlead setup
4. Verify you have credentials for every inbox you intend to connect; do not proceed with partial credentials
5. Keep the credentials document open during the next steps

Benchmark: Credential gathering for 5 inboxes takes 5–10 minutes. For 10+ inboxes, use the bulk export to save time.

Failure mode: Gathering credentials for fewer inboxes than you plan to connect, then having to return to Inframail mid-setup. Batch the credential export before starting Smartlead configuration.

Step 2: Add the first inbox to Smartlead

What to do: Add your first Inframail inbox to Smartlead as a connected email account and verify the connection.

Sub-steps:

1. Log in to Smartlead and navigate to Email Accounts (or Sending Accounts, depending on your Smartlead version)
2. Select "Add Account" or the equivalent option for adding a new sending account
3. Choose the SMTP/IMAP option (not Google or Microsoft OAuth — Inframail uses custom credentials)
4. Enter the SMTP settings: from name (your name or company representative's name), from email (the full Inframail inbox address), SMTP host (smtp.office365.com), SMTP port (587), username (full email address), password
5. Enter the IMAP settings: IMAP host (outlook.office365.com), IMAP port (993), username (full email address), same password
6. Save and test the connection; Smartlead will send a test email and verify IMAP access
7. Confirm the test email arrives in your test recipient's inbox — if it does not, check spam folder and note whether authentication headers are showing as pass in the email headers

Benchmark: Adding and verifying one inbox in Smartlead takes 3–7 minutes including the test email wait.

Failure mode: Selecting "Sign in with Microsoft" or "Sign in with Google" instead of the manual SMTP option. Inframail inboxes cannot be connected via OAuth because they use a custom Microsoft 365 provisioning model. Always use the SMTP/IMAP manual connection option.

Step 3: Set daily sending limits for the connected inbox

What to do: Configure the daily sending limit for each inbox in Smartlead immediately after connection, before adding more inboxes.

Sub-steps:

1. In the Smartlead email account settings for the newly connected inbox, find the sending limit or daily limit setting
2. Set the daily email limit based on inbox maturity: 10–20 for inboxes in early warmup (weeks 1–4), 30–40 for moderately warmed inboxes (weeks 5–8), 40–50 maximum for fully matured inboxes (8+ weeks)
3. Set the sending window to business hours in the target market's timezone (e.g., 8am–6pm EST for US-targeted campaigns)
4. Enable send interval randomisation if Smartlead offers it — spacing sends at random 2–5 minute intervals rather than fixed intervals reduces pattern detection by spam filters
5. Save the settings before proceeding to the next inbox

Benchmark: Configuring sending limits for one inbox takes 2–3 minutes.

Failure mode: Setting limits too high for inbox age. New inboxes pushing 50 emails per day in week one produce a volume spike that triggers spam filter pattern detection. The limit must match the warmup timeline, not your campaign volume targets.

Step 4: Connect all remaining Inframail inboxes

What to do: Repeat the connection process for all remaining Inframail inboxes, configuring sending limits for each.

Sub-steps:

1. Repeat Steps 2 and 3 for each additional inbox from your credential list
2. After connecting all inboxes, navigate to Email Accounts in Smartlead to confirm all accounts show as connected (not "failed" or "pending")
3. If any account shows as failed, revisit the credential entry for that inbox and check for typos or format errors
4. Note the total daily sending capacity: number of connected inboxes × per-inbox daily limit = your current total daily capacity

Benchmark: With the process streamlined from Step 2, adding each subsequent inbox should take 2–5 minutes.

Failure mode: Missing the IMAP settings for some inboxes while connecting. IMAP is required for Smartlead to detect replies and enable warmup. An inbox connected without IMAP will send but not receive, which prevents reply handling and warmup engagement.

Step 5: Enable warmup for each connected inbox

What to do: Activate warmup for each Inframail inbox connected to Smartlead, either using Smartlead's built-in warmup or Instantly's warmup tool.

Sub-steps (Smartlead warmup):

1. In Smartlead's email account settings, find the warmup option
2. Enable warmup for each inbox
3. Set initial warmup volume: 10–20 warmup emails per day for new inboxes
4. Confirm warmup is showing as active for each inbox before proceeding to campaign setup

Sub-steps (Instantly warmup as alternative):

1. Connect each Inframail inbox to Instantly separately using the same SMTP/IMAP credentials
2. Enable Instantly's warmup feature for each inbox in Instantly
3. Run warmup through Instantly while simultaneously using Smartlead for campaign sending after the warmup period is complete
4. Note: connecting the same inbox to two tools (Instantly for warmup, Smartlead for campaigns) is a common and effective pattern, but avoid having both tools send campaign emails from the same inbox simultaneously

Benchmark: Warmup activation takes 5 minutes per inbox. Warmup must run for 14–28 days before campaigns begin.

Failure mode: Turning off warmup when campaigns start. Warmup should continue running alongside campaigns indefinitely. The positive engagement signals from warmup emails partially offset the neutral/negative signals from cold outreach and help maintain inbox reputation over time.

Step 6: Create a campaign in Smartlead and assign inboxes

What to do: Create your first cold email campaign in Smartlead and assign the Inframail inboxes that will rotate sends across the campaign.

Sub-steps:

1. In Smartlead, navigate to Campaigns and create a new campaign
2. In the campaign settings, find the "Sending Accounts" or "Email Accounts" section and assign the Inframail inboxes you want to use for this campaign
3. Assign 3–10 inboxes per campaign depending on your sending volume target and inbox availability
4. Confirm Smartlead's rotation setting: by default, Smartlead should distribute sends across all assigned inboxes; verify this is active rather than sending from one inbox sequentially
5. Set the campaign's daily volume target based on total inbox capacity (number of assigned inboxes × per-inbox daily limit)

Benchmark: Campaign setup including inbox assignment takes 15–30 minutes including sequence writing and scheduling.

Failure mode: Assigning too many inboxes to a single campaign. Splitting sends across 20 inboxes in one campaign means each inbox sends very few emails per day, making it harder to monitor per-inbox performance and harder to identify which inboxes are underperforming. 3–10 inboxes per campaign is the manageable range.

Step 7: Set up deliverability monitoring

What to do: Configure the monitoring setup that will alert you to deliverability problems before they compound into significant damage.

Sub-steps:

1. In Smartlead's campaign analytics, identify the per-inbox metrics: open rate, reply rate, bounce rate, and unsubscribe rate per sending account
2. Set alert thresholds: pause any inbox with bounce rate above 5% or complaint indicator above 0.3%
3. Set a weekly review schedule: at minimum weekly, review per-inbox open rates and bounce rates across all active campaigns
4. Set up Google Postmaster Tools monitoring for each sending domain: add each domain and monitor the domain reputation and spam rate graphs
5. Check MXToolbox blacklist checker for each sending domain at least monthly; add it to a calendar reminder

Benchmark: Initial monitoring setup takes 30–60 minutes. Weekly review takes 15–30 minutes once the dashboard is established.

Failure mode: Monitoring at campaign level only, not at inbox level. A campaign average can look healthy while individual inboxes are degrading significantly. Per-inbox monitoring is essential for identifying problems before they spread to other inboxes assigned to the same campaign.

Step 8: Upload contacts and launch the campaign

What to do: Load your verified contact list into Smartlead and launch the campaign after confirming all configuration is correct.

Sub-steps:

1. Prepare your contact CSV with at minimum: email, first name, last name, company name (required for personalisation tokens)
2. In Smartlead, upload contacts to the campaign; Smartlead will validate the CSV format and flag any missing required columns
3. Review the campaign sequence one final time: check personalisation tokens, confirm follow-up timing, verify CTA is clear
4. Run an inbox placement test (GlockApps or Mail-Tester) from one of the assigned inboxes before launching to confirm inbox vs. spam placement
5. Launch the campaign and monitor the first 24–48 hours closely: check that emails are sending, that replies are being detected, and that no inboxes show unusual bounce rates on day one

Benchmark: Contact upload for 5,000 contacts takes 5–15 minutes depending on connection speed and Smartlead's processing time.

Failure mode: Uploading unverified contacts to a new inbox setup. High bounce rates from unverified contacts during the first campaign can damage inbox reputation before it has fully matured. Use verified contacts from Quarvio to prevent this.

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Inframail-to-Smartlead configuration reference

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Advanced tactics

Tactic 1: Separate warmup tool from campaign tool for reliability

Running warmup through Smartlead and campaigns through Smartlead from the same inbox is functional, but introduces a dependency: if your Smartlead account has an issue (billing lapse, account flag, temporary outage), both warmup and campaigns stop simultaneously. The alternative is to run warmup through Instantly and campaigns through Smartlead from the same Inframail inbox.

Because SMTP/IMAP credentials can be used by multiple tools simultaneously (Inframail does not restrict credential use to one tool), this is technically possible. The inbox receives warmup sends from the Instantly pool and sends campaign emails via Smartlead's campaign engine. The positive warmup engagement signals from Instantly help offset the cold outreach signals from Smartlead's campaigns.

The operational rule: only Smartlead sends campaign emails from this inbox. Only Instantly sends warmup emails. Do not configure Smartlead's warmup AND Instantly's warmup for the same inbox simultaneously — this doubles the warmup send count and can cause over-sending.

Tactic 2: Segment domains by target industry for reputation isolation

If you are running cold email campaigns across multiple industries or audience segments, assign separate sending domains to each segment. One domain for technology prospects, one for finance, one for healthcare. Each domain's Inframail inboxes connect to Smartlead as a separate sending pool.

The deliverability benefit: if the technology segment's contact data has higher bounce rates than expected (a common situation when lists are not fresh), the resulting reputation damage stays on the technology domain. The finance and healthcare domains' reputations are unaffected. You can pause the technology domain, address the list quality issue, and resume without rebuilding your entire sending infrastructure.

Configure Smartlead campaigns with domain-specific inbox assignments: Technology Campaign uses only technology-domain inboxes. Finance Campaign uses only finance-domain inboxes. This setup also makes per-segment attribution cleaner.

Tactic 3: Use Smartlead's inbox rotation to A/B test sending personas

Smartlead's inbox rotation assigns recipients to different sending inboxes across a campaign. This can be used strategically to A/B test different sending personas (different names, different "From" email structures) to understand which persona drives better reply rates with a specific audience.

Configuration: create two sets of Inframail inboxes with different sending names (e.g., "Ryan Mercer" from ryan@domain1.com vs. "Sarah Chen" from sarah@domain2.com). Assign both inbox sets to the same Smartlead campaign. After 200+ sends per persona, compare reply rates. The winning persona becomes the primary sender for future campaigns to similar audiences.

This approach uses your inbox rotation infrastructure to run a natural persona test without requiring separate campaigns or complex split testing configuration.

Tactic 4: Monitor per-inbox performance weekly and rotate underperformers

Not all inboxes in a rotation perform equally over time. Some accumulate positive reputation signals faster; others encounter list segments with higher complaint rates. Weekly per-inbox monitoring allows you to identify divergence before it becomes a crisis.

The practice: every Monday, export per-inbox metrics from Smartlead for the previous week (open rate, bounce rate, reply rate per sending account). Any inbox with bounce rate above 3% or open rate more than 15 percentage points below the campaign average gets paused and investigated before the next campaign goes live.

Pausing a single inbox for a week while investigating does not materially impact campaign volume if you have 5+ inboxes in rotation. Leaving a degrading inbox in rotation for 3–4 weeks can accelerate reputation damage to the point where the inbox needs to be rebuilt.

Tactic 5: Use Smartlead's reply handling to manage inbox capacity

Smartlead detects replies and can be configured to automatically remove replied contacts from future sequence steps. This is important for Inframail inbox capacity planning: if a campaign generates significant reply volume, the inbox that sent the initial email receives those replies in addition to continuing to send sequence follow-ups. High reply volume can push an inbox toward its daily limit on the IMAP side.

Configure Smartlead to distribute reply-heavy campaigns across more inboxes than low-reply campaigns. Campaigns to highly engaged segments (where you expect 10%+ reply rates) should have more inboxes in rotation and lower per-inbox daily limits than standard campaigns. This prevents any single inbox from becoming a reply processing bottleneck.

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Troubleshooting Inframail-Smartlead connection issues

Problem 1: SMTP connection test failing in Smartlead

Symptoms: After entering Inframail SMTP credentials in Smartlead, the connection test fails with an authentication error or timeout.

Diagnosis steps:

1. Verify the SMTP port is 587 (not 465 or 25)
2. Verify the security setting is STARTTLS (not SSL/TLS, which is for IMAP)
3. Confirm the username is the full email address (not just the first part)
4. Confirm the password is from Inframail's inbox-specific credentials, not your Inframail account login password
5. Check whether Inframail has a service status page showing any Microsoft 365 provisioning issues

Fix: The most common cause is incorrect port or security settings. Port 587 + STARTTLS is the correct combination for Microsoft 365 SMTP. Port 993 + SSL/TLS is for IMAP. Mixing these up causes authentication failures.

Problem 2: Inbox showing connected but emails not sending

Symptoms: The Inframail inbox shows as connected in Smartlead but campaign emails are not being sent from it.

Diagnosis steps:

1. Check whether the inbox has a daily limit of 0 (it may still be in warmup-only mode with campaigns disabled)
2. Check whether the inbox is actually assigned to the active campaign in Smartlead's campaign settings
3. Check whether the campaign has leads uploaded and the campaign is in "Active" status rather than "Paused" or "Draft"
4. Check the inbox error log in Smartlead's email account settings for any recent send failures

Fix: Verify daily limit is above 0, inbox is assigned to the campaign, and campaign is in active status. If all three are correct and sending still is not occurring, re-test the SMTP connection manually and contact Smartlead support with the specific error log.

Problem 3: Replies not being detected in Smartlead

Symptoms: Prospects are replying to campaign emails but Smartlead is not showing the replies or automatically removing them from the sequence.

Diagnosis steps:

1. Verify IMAP settings are correctly configured: server outlook.office365.com, port 993, SSL/TLS security
2. Check whether IMAP is enabled for this inbox in Inframail (IMAP access must be enabled at the Inframail level, not just in Smartlead)
3. Verify the email address entering replies is the same address connected to Smartlead's IMAP — if your Inframail inbox forwards replies to a different address, Smartlead may not see them

Fix: IMAP connectivity issues are the primary cause of missed reply detection. Re-enter IMAP credentials from scratch (not copy-paste from previous attempt). If IMAP is confirmed correct and replies still are not detected, check whether Smartlead's IMAP polling frequency is set to a reasonable interval (every 15–30 minutes is standard).

Problem 4: High bounce rates from the first campaign send

Symptoms: Within the first 24–48 hours of campaign launch, bounce rates are above 5% across inboxes.

Diagnosis steps:

1. Check whether the contact list was verified before upload; unverified lists have 10–25% bounce rates typically
2. Check whether the bounce addresses are from one specific domain (indicating a domain-level deliverability issue with the sending domain rather than list quality)
3. Check whether hard bounces and soft bounces are being correctly distinguished; soft bounces (temporary delivery failures) should not be counted at the same threshold as hard bounces

Fix: Stop the campaign immediately if bounce rates are above 5%. The primary fix is contact list quality — verified contacts from Quarvio prevent this. Secondary fix is removing hard-bounced addresses from your list before resuming. Do not resume campaigns from inboxes that generated more than 5% hard bounce rates without first identifying and fixing the root cause.

Problem 5: Warmup score declining after connecting to Smartlead

Symptoms: Inbox warmup scores were improving while warmup-only, but declined after campaign sends began through Smartlead.

Diagnosis steps:

1. Check campaign complaint rate: if the cold email campaign is generating complaints, those complaints offset warmup positive signals
2. Check whether campaign volume exceeded the per-inbox daily limit, causing over-sending
3. Check whether the same inbox is running warmup AND campaigns simultaneously from both Smartlead and another tool, doubling the total daily send count

Fix: Reduce campaign volume from this inbox. If complaint rate is the issue, review campaign targeting and message relevance. If over-sending is the issue, lower the daily limit in Smartlead. Allow warmup 1–2 additional weeks at reduced campaign volume before re-evaluating.

Problem 6: Smartlead showing "daily limit reached" for an inbox earlier than expected

Symptoms: Inboxes in Smartlead show as having reached their daily limit before the expected sending volume has been reached.

Diagnosis steps:

1. Check whether warmup emails are being counted toward the daily limit in Smartlead — some configurations count all outbound emails (warmup + campaign) against the same limit
2. Check whether the limit set in Smartlead matches the intended configuration
3. Check whether multiple campaigns are assigned to the same inbox, with their combined volume exceeding the limit

Fix: If warmup emails are counting toward the campaign limit, either increase the daily limit to accommodate both warmup and campaign volume, or use a separate tool (Instantly) for warmup so warmup sends are not counted in Smartlead's limit tracking.

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What practitioners say about Inframail and Smartlead

A verified user on Inframail reviews on G2:

"The Inframail and Smartlead combination is my standard setup for clients. Inframail for inboxes, Smartlead for campaigns. The SMTP connection is straightforward — it is just entering credentials. The thing that took me longest to get right was the rotation and daily limit configuration, not the connection itself."

— Verified buyer on Inframail reviews on G2

A thread in r/coldemail (512 upvotes) on the warmup question:

"If you are going Inframail + Smartlead, decide on your warmup strategy before connecting. Option 1: Smartlead's built-in warmup on every inbox. Option 2: Instantly warmup + Smartlead campaigns. Both work but mixing them up (having two tools warming the same inbox) causes sending volume to double. Pick one and stick to it."

— r/coldemail, 512 upvotes

A verified reviewer on Instantly reviews on G2 comparing the two sending tools:

"I use Instantly for warmup across all inboxes regardless of which tool I do campaigns in. Instantly's warmup network is large and the scores are reliable. For clients who prefer Smartlead's campaign UX, I keep the warmup running in Instantly and just route campaign sends through Smartlead. The inboxes stay warm without Smartlead warmup."

— Verified buyer on Instantly reviews on G2

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Our actual stack

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Frequently asked questions

Can I use the same Inframail inbox in both Smartlead and Instantly simultaneously?

Yes. Inframail's SMTP and IMAP credentials can be used by multiple tools simultaneously. The common practice is to use Instantly for warmup and Smartlead for campaign sends from the same inbox. The key restriction: do not send campaign emails from the same inbox through both tools at the same time, as this doubles campaign volume and can cause over-sending. Use each tool for a specific function (warmup vs. campaigns) rather than having both send campaigns.

What SMTP and IMAP settings does Inframail use?

SMTP: server smtp.office365.com, port 587, security STARTTLS, username (full email address), password (inbox-specific credential from Inframail). IMAP: server outlook.office365.com, port 993, security SSL/TLS, username (full email address), same password. These settings apply to all Inframail inboxes regardless of your specific domain.

How many inboxes should I assign to one Smartlead campaign?

Three to ten inboxes per campaign is the manageable range. Below three, the rotation distributes sends across too few inboxes and individual inbox load is higher. Above ten, it becomes difficult to monitor per-inbox performance and identify which specific inboxes are underperforming. For higher total volume, run multiple campaigns with 3–10 inboxes each rather than one campaign with 20+ inboxes.

Does Smartlead handle reply detection automatically with Inframail inboxes?

Yes, provided IMAP is correctly configured. Smartlead polls the IMAP server at regular intervals to check for new replies. When a reply is detected, Smartlead can automatically stop sending further sequence steps to that prospect. Correct IMAP configuration (server, port, security, credentials) is required; the connection test in Smartlead verifies IMAP access as part of the setup flow.

What is the best way to warm up Inframail inboxes when using Smartlead?

Two options: use Smartlead's built-in warmup feature, or connect each inbox to Instantly for warmup while using Smartlead for campaigns. Both work. The advantage of Instantly for warmup is its large warmup network and the warmup score visibility, which makes it easier to confirm warmup progress. The advantage of Smartlead's built-in warmup is that all inbox management stays in one tool.

How long before I can start campaigns after connecting Inframail inboxes to Smartlead?

14–28 days minimum after warmup begins. New inboxes should not send cold campaign emails until they have completed at least 14 days of warmup. For high-volume operations (40+ emails per inbox per day), 28–60 days of warmup before full campaign volume is the safer benchmark.

What bounce rate should cause me to pause an inbox in Smartlead?

Pause any inbox with a bounce rate above 5% on a campaign send. Hard bounces (permanent delivery failures) above 3% are a serious signal. Soft bounces (temporary failures) are more acceptable but should still be monitored. High bounce rates damage sender reputation; the longer a high-bounce inbox stays in active sending, the more reputation damage accumulates.

Can I connect Inframail inboxes to Smartlead via API instead of SMTP?

Smartlead does not have a native Inframail integration; SMTP/IMAP is the connection method. Smartlead's API can be used for campaign management (creating campaigns, uploading leads, retrieving analytics) but not for inbox provisioning. Inbox connections are done through the Smartlead interface using the SMTP/IMAP settings.

How do I know if my Inframail inboxes are sending correctly through Smartlead?

After campaign launch, check: (1) Smartlead's activity log shows emails being sent from the correct inboxes, (2) the test email you sent during setup arrived in inbox (not spam), (3) per-inbox sent count is increasing in Smartlead's analytics. If sent count for a specific inbox is zero after 24 hours of the campaign running, that inbox has a connection or limit issue.

What should I do if an Inframail inbox gets blocklisted while connected to Smartlead?

Pause the inbox in Smartlead immediately (remove it from the campaign's sending account list). Check MXToolbox to identify the specific blocklist. Submit a removal request on that blocklist's removal form. Investigate the root cause: typically high bounce rate or high complaint rate from campaign sends. Fix the root cause. Re-add the inbox to warmup-only mode for 2–4 weeks before returning it to campaigns.

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