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How to set up Inframail end-to-end: domain purchase, DNS configuration, inbox provisioning, SMTP export, Instantly connection, and warmup handoff before first campaign.
Sarah Okonkwo
Sales ops specialist, deliverability obsessive · Updated June 24, 2026
Last updated: June 2026 · Sarah Okonkwo, Sales ops specialist, deliverability obsessive
TL;DR — 7 things to know before reading
The cold email infrastructure setup problem is not technical — it is sequencing. Every component of a working cold email stack (domain, DNS, inbox, warmup, sending tool, contact list) has dependencies on the components before it, and getting the order wrong adds days or weeks to setup time. The teams that set up Inframail quickly are not necessarily more technical than teams that struggle. They just know the right order: domain first, DNS second, inbox provisioning third, warmup fourth, contacts fifth, campaigns last.
Inframail's specific value in this sequence is what it automates. Manual Microsoft 365 inbox provisioning without Inframail requires creating a tenant, adding users, configuring DNS manually, setting up MFA exceptions for SMTP auth, and managing license renewals per inbox. Inframail handles all of that behind its interface. You connect a domain, create inboxes, and export credentials. The underlying Microsoft 365 infrastructure is managed for you. For teams running 10+ inboxes across multiple domains, this automation represents a meaningful operational saving.
The warmup requirement is the most commonly skipped step. New inboxes that send cold email immediately from day one typically develop reputation problems within the first two weeks: complaint rates climb, open rates fall, and some inboxes get throttled or blocked before the campaign has run long enough to produce any meaningful result. The 14–28 day warmup period is not a bureaucratic requirement; it is the time it takes for email infrastructure to establish the positive sending history that recipient filters use to make inbox placement decisions. Skip it at your own risk, and understand the risk clearly: a damaged new inbox is effectively a wasted domain until a 4–6 week recovery warmup is completed.
Inframail handles the inbox provisioning and DNS automation. Instantly handles sending, warmup, and campaign management. Quarvio delivers the verified contact data that keeps bounce rates below the 5% threshold where inbox reputation starts degrading. Aimfox runs the LinkedIn channel alongside email campaigns, targeting the same prospects across both channels to increase total response rates.
Inframail is a cold email infrastructure platform that provisions Microsoft 365 inboxes at scale with automated DNS configuration and SMTP credential export. Three features distinguish it from alternatives:
Microsoft 365 as the underlying provider. Inframail inboxes run on Microsoft's Office 365 mail servers, not on a proprietary sending infrastructure. This matters for deliverability because Microsoft 365 inboxes carry the sender reputation of a commercial email provider that recipient filters treat with higher trust than bulk ESP servers. Gmail and Outlook recipient filters are configured to recognise Microsoft 365 sending infrastructure. Inboxes on this infrastructure start with better default placement odds than inboxes on shared ESP infrastructure.
Automated DNS configuration. When you add a domain to Inframail, it generates the correct SPF, DKIM, and DMARC records for your Microsoft 365 inboxes. You add these records to your registrar's DNS panel and verify them in Inframail. No manual record construction required. This reduces the most error-prone step in the setup process to a copy-paste operation.
Flat pricing per domain. Inframail charges a flat monthly fee per domain regardless of the number of inboxes you create on that domain. Once you scale past 5–6 inboxes per domain, Inframail is typically cheaper than per-seat providers. For operations running 20+ inboxes, the cost difference is substantial.
The alternative for cold email senders is manual Microsoft 365 provisioning (complex, expensive per seat), Google Workspace (better personal reputation but stricter bulk sending limits), or shared ESP infrastructure (lower cost, lower deliverability baseline). Inframail sits at the intersection of Microsoft 365 quality and manageable cost for cold email volumes.
A sending domain purchased and ready. You need a domain that is not your primary business domain. Never use your main company domain (yourcompany.com) for cold email sending. Use a variation: getmeetyourcompany.com, yourcompanyhq.com, teamyourcompany.com. The sending domain takes all deliverability risk; if it gets blocklisted, your primary domain is unaffected.
Access to your domain's DNS panel. You need to be able to add TXT records to your domain's DNS. Most registrars provide a DNS panel in their control interface. Confirm you have access before starting setup. Common registrars with straightforward DNS panels: Namecheap, Cloudflare, GoDaddy, Google Domains (now Squarespace Domains).
An Inframail account. Sign up at Inframail.io. Setup takes 2–5 minutes. No credit card required to start the trial period.
An Instantly account. You will connect Inframail's SMTP credentials to Instantly for campaign sending and warmup. Sign up for Instantly separately if you have not already. Per Instantly's pricing page, plans start at Growth $30/month.
Verified contact data. Have your contact list ready before completing the setup. Quarvio delivers pre-verified B2B contacts at $129 for 5,000 through $699 for 50,000 contacts. Starting campaigns with unverified data when your inboxes are newly warmed is the fastest route to reputation damage.
What to do: Sign up for Inframail and familiarise yourself with the dashboard structure before adding any domains or inboxes.
Sub-steps:
Benchmark: Account creation to dashboard access takes 5–10 minutes including email verification.
Failure mode: Adding inboxes before completing DNS setup. Inboxes created before DNS records are correctly configured will not authenticate properly and will fail deliverability checks. Always complete DNS setup and verification before creating inboxes.
What to do: Add the domain you purchased for cold email sending to your Inframail account. This is the domain that will appear in the "From" address of your cold emails.
Sub-steps:
Benchmark: Adding a domain and receiving DNS records takes less than 2 minutes.
Failure mode: Adding the wrong domain. Confirm the domain you are adding matches the domain you purchased and intend to use for sending. Adding yourcompany.com instead of meetyourcompany.com is a costly mistake that routes all authentication records to the wrong domain.
What to do: Add the three DNS records Inframail generated (SPF, DKIM, and DMARC) to your domain's DNS configuration at your registrar.
Sub-steps:
v=spf1 include:spf.protection.outlook.com -all (Inframail provides the exact string)selector1._domainkey) and the value pointing to Microsoft's DKIM infrastructurep=none is acceptable initiallyBenchmark: Adding three DNS records takes 5–15 minutes depending on your registrar's interface. Some registrars require separate saves for each record; others allow bulk editing.
Failure mode: Entering records in the wrong fields. TXT records have a "host" field and a "value" field. The SPF and DMARC TXT records typically have @ as the host (meaning the root domain) and the full record string as the value. The DKIM CNAME has a specific host subdomain (e.g., selector1._domainkey) and a CNAME value. Mixing up host and value produces broken records that fail verification.
What to do: Wait for DNS records to propagate and then verify them through Inframail's verification tool and an external checker.
Sub-steps:
Benchmark: DNS propagation for most registrars takes 15–60 minutes for TXT records. CNAME records (used for DKIM) sometimes propagate faster. Check at 20 minutes and again at 60 minutes; if not propagated by 2 hours, review the records for errors.
Failure mode: Checking before propagation and concluding records are wrong. DNS propagation has latency. A record that appears to fail at 5 minutes post-creation often passes at 60 minutes. Check the record syntax first; if it looks correct, wait the full propagation window before troubleshooting.
What to do: Create the sending inboxes on your verified domain. Each inbox is a separate email address that will send cold emails.
Sub-steps:
Benchmark: Each inbox takes 1–3 minutes to provision. Creating 10 inboxes takes 10–30 minutes.
Failure mode: Creating too many inboxes before warmup. Creating 20 inboxes and immediately connecting all of them to campaigns without warmup produces 20 damaged inboxes simultaneously. Create only the inboxes you plan to warm up in the current period, then add more as you scale.
What to do: Export the connection credentials for each inbox so you can connect them to Instantly or another sending tool.
Sub-steps:
Benchmark: Credential export for a single inbox takes 2–3 minutes. Bulk export for 10 inboxes takes 5 minutes.
Failure mode: Copying incomplete credentials. SMTP connections require all five parameters: server, port, security protocol, username, and password. Missing any one will cause a connection failure in Instantly. Double-check completeness before proceeding.
What to do: Add each Inframail inbox to Instantly using the SMTP/IMAP credentials.
Sub-steps:
Benchmark: Connecting one inbox to Instantly takes 3–5 minutes including the test send. Connecting 10 inboxes takes 30–50 minutes.
Failure mode: Using OAuth instead of SMTP/IMAP credentials. Inframail inboxes cannot be connected via Microsoft OAuth because they use a custom provisioning model. The SMTP/IMAP credential method is required. If Instantly prompts for OAuth or shows "Sign in with Microsoft", select the manual SMTP option instead.
What to do: Activate Instantly's warmup feature for each newly connected inbox before running any cold email campaigns.
Sub-steps:
Benchmark: Per Woodpecker's email warmup guide, minimum warmup time is 2–4 weeks, with 8–12 weeks for full maturity. At 14 days, inboxes can begin low-volume cold sending (10–20 emails per day). At 28 days, moderate volume (30–50 per day). At 60+ days, full volume.
Failure mode: Stopping warmup when cold campaigns begin. Warmup should continue running alongside cold campaigns indefinitely. The warmup emails generate positive engagement signals (opens, replies, non-spam marks) that offset the neutral or negative signals from cold outreach. Turning off warmup when campaigns start removes this positive signal contribution.
What to do: Configure per-inbox daily sending limits in Instantly to prevent over-sending from any single inbox.
Sub-steps:
Benchmark: At 40 emails per inbox per day across 5 inboxes, you can send 200 emails per day. At 10 inboxes, 400 per day. At 25 inboxes across 5 domains, 1,000 per day. Plan your inbox count based on your daily volume target.
Failure mode: Setting limits too high too soon. Pushing new inboxes to 50 emails per day in week one produces a spike in sending volume that triggers spam filters trained on normal corporate email patterns. The volume ramp must match the warmup timeline.
What to do: Run a pre-campaign deliverability check to confirm authentication, reputation, and placement are at acceptable levels before sending to your contact list.
Sub-steps:
Benchmark: All three authentication records should show as pass. Inbox placement test should show inbox (not spam) at Gmail and Outlook for at least 70% of test sends. Below 70% inbox placement indicates a warmup or authentication issue requiring resolution before campaign launch.
Failure mode: Skipping the pre-campaign check. The pre-campaign check takes 30 minutes but can save weeks of campaign recovery if it identifies a configuration problem before cold sends begin. Authentication failures and blocklist appearances caught at this stage are easy to fix; caught after 1,000 campaign sends, they require infrastructure rebuilding.
| Setting | Recommended value | Notes |
|---|---|---|
| Inboxes per domain | 3–5 | Spreading inboxes across domains limits per-domain reputation exposure |
| Sending domains per brand | 3–5 | Protects primary domain if one sending domain is flagged |
| Daily emails per inbox | 30–50 (mature) | Lower in warmup phase: 10–20 in weeks 3–4 |
| Warmup minimum duration | 14 days | 28–60 days for high-volume targets |
| Warmup daily volume | Start 10, ramp to 40 | Increase by 5–10 emails per day per week |
| SMTP port | 587 (STARTTLS) | Standard Microsoft 365 SMTP port |
| IMAP port | 993 (SSL/TLS) | Required for reply detection in Instantly |
| DNS propagation wait | 15–60 minutes | Full propagation can take up to 48 hours |
| DMARC starting policy | p=none | Move to p=quarantine after 30 days of monitoring |
| Pre-campaign inbox placement target | 70%+ inbox | Below 70% indicates warmup or authentication issue |
The standard Inframail setup uses one domain with multiple inboxes. The advanced setup uses multiple domains with multiple inboxes each, creating a portfolio that isolates risk and enables higher total sending volume.
A 5-domain portfolio with 5 inboxes per domain gives you 25 inboxes. At 40 emails per inbox per day, that is 1,000 emails per day. If one domain encounters a deliverability issue (elevated complaint rate, temporary blocklist), you pause that domain's campaigns while the other four continue. This isolation means one bad campaign batch does not shut down your entire outreach operation.
The portfolio also enables targeting segmentation: use Domain A for campaign to Segment A, Domain B for Segment B. If Segment A turns out to have worse list quality than expected (higher bounce rate), the damage stays on Domain A without contaminating Domain B's reputation.
Domain age is a reputation factor. A domain registered today and immediately set up with Inframail has no sending history. A domain registered 90 days ago and aged (with DNS records set and some low-volume sends in warmup) arrives at the first campaign with more established reputation signals.
The practice: register domains 60–90 days before you intend to use them for campaigns. Set up the DNS records immediately and run warmup at very low volume (5–10 emails per day) during the aging period. By the time you ramp to campaign volume, the domain has 2–3 months of positive sending history. This produces noticeably better initial inbox placement rates compared to campaigns launched from day-zero domains.
As you add more sending domains, naming becomes an operational challenge. A systematic approach: use a consistent prefix or suffix pattern that identifies the domain as a sending domain without looking obviously templated to recipients.
Patterns that work: prefixing with "meet" (meetacmeco.com), "team" (teamacmeco.com), "go" (goacmeco.com). Patterns to avoid: numbered domains (acmeco1.com, acmeco2.com) which are recognisable spam patterns; obviously generic domains (bestservices2026.com); domains with hyphens in obvious positions.
Document your domain portfolio in a spreadsheet with: domain name, registrar, date registered, date DNS configured, current warmup status, assigned campaign segments, and reputation monitoring links (Postmaster Tools URL, blacklist check date). This documentation prevents operational confusion as the portfolio grows.
Inframail's value is in providing multiple clean inboxes. The operational question is how to assign contacts to inboxes for maximum deliverability control. Two approaches:
Domain-based segmentation: All emails to contacts in one industry or segment go through one domain's inboxes. If that segment has worse-than-expected list quality, the reputation impact is contained to that domain.
Round-robin rotation: Contacts are distributed evenly across all inboxes regardless of segment. This maximises volume distribution but makes it harder to trace deliverability issues to specific list segments.
For most operations, domain-based segmentation with round-robin rotation within each domain's inbox pool is the right balance: segment isolation at the domain level, volume distribution at the inbox level.
Instantly's warmup feature generates a warmup score per inbox based on positive engagement signals from warmup emails. This score is a leading indicator of deliverability health. An inbox with a warmup score trending up (more opens, replies, and good engagement from warmup) will have better cold campaign inbox placement than one with a flat or declining score.
Before scaling an inbox from warmup-only to active campaigns, check the warmup score trend over the past 7 days. If the score is improving, the inbox is ready to add campaigns. If the score is flat or declining, extend warmup by another 1–2 weeks before adding campaigns. This practice prevents launching campaigns from inboxes that have not yet established the positive reputation signals that produce good inbox placement.
Symptoms: Inframail's DNS verification shows FAIL for SPF, DKIM, or DMARC even after you have added the records to your registrar.
Diagnosis steps:
@ (root domain); DKIM uses a specific subdomain like selector1._domainkeyFix: The most common cause is a registrar that adds extra quotes around TXT record values. If MXToolbox shows your SPF record with double-quotes inside double-quotes ("\"v=spf1...\""), remove the outer quotes in your registrar. Re-verify after another propagation wait.
Symptoms: Instantly shows a connection error when you attempt to connect an Inframail inbox using SMTP/IMAP credentials.
Diagnosis steps:
Fix: The most common cause is entering the Inframail account password instead of the per-inbox SMTP password, or using the username portion without the full email address format. Retrieve the exact credentials from Inframail's inbox settings and re-enter all five parameters from scratch.
Symptoms: Warmup emails sent from new Inframail inboxes are landing in spam rather than inbox at warmup pool recipients.
Diagnosis steps:
Fix: Authentication failures are the most common cause of warmup-phase spam placement. Fix the failing record first. If authentication is passing and warmup emails are still going to spam, reduce the daily warmup volume and allow more time before checking again.
Symptoms: SPF and DMARC pass verification, but DKIM continues to show as failing even after 24 hours.
Diagnosis steps:
selector1._domainkey with no domain suffix — some registrars auto-append the domain, others require you to enter the full subdomain)Fix: Some registrars auto-append the root domain to CNAME records entered with relative hosts. If Inframail says enter selector1._domainkey and your registrar auto-appends the domain, the record becomes selector1._domainkey.yourdomain.com.yourdomain.com which is incorrect. Enter the full absolute host selector1._domainkey.yourdomain.com (with trailing dot if your registrar requires it) to prevent auto-appending.
Symptoms: The warmup score in Instantly is trending down over 5–7 days rather than improving.
Diagnosis steps:
Fix: Fix IMAP connectivity first if that is the issue. Ensure cold campaigns are not running simultaneously with early warmup. If the IMAP is correct and no campaigns are running, contact Instantly support to investigate warmup pool behaviour.
Symptoms: MXToolbox shows your sending domain on a blocklist, or inbox placement tests show very high spam rates (80%+).
Diagnosis steps:
Fix: Stop all sending from the blocked domain immediately. Request removal from the specific blocklist (most have a removal request form). Investigate and fix the root cause — usually high bounce rate from poor list quality or high complaint rate from broad targeting. Do not resume sending until removal is confirmed and root cause is addressed.
Symptoms: After 28 days of warmup, inbox placement tests still show significant spam placement (above 30% spam).
Diagnosis steps:
Fix: Extend warmup by 2–4 more weeks with increased daily warmup volume. Fix any authentication failures. If cold campaigns were started too early, pause them for 2–4 weeks while warmup continues before re-attempting.
A verified user on Inframail reviews on G2:
"The DNS automation is the real time-saver. Before Inframail, I was manually setting up SPF, DKIM, and DMARC for every new domain and making mistakes that took days to troubleshoot. Now I add the domain, copy the records Inframail generates, and I'm done. Setup that used to take half a day now takes an hour."
— Verified buyer on Inframail reviews on G2
A discussion in r/coldemail (634 upvotes) on the warmup step:
"The one thing I wish I knew before setting up Inframail: do not skip warmup. I connected 10 inboxes to Instantly and immediately launched a 500-email campaign. Had three inboxes flagged within a week. Had to rebuild. The warmup step looks optional but it is not. Four weeks minimum."
— r/coldemail, 634 upvotes
A second verified G2 reviewer on Inframail reviews on G2:
"For agencies managing multiple clients, Inframail's flat per-domain pricing completely changes the economics. We were paying $8–12 per inbox per month at previous providers. At 50 inboxes per client and 10 clients, the savings are significant. The setup is slightly more technical than plug-and-play tools but the cost and deliverability quality justify it."
— Verified buyer on Inframail reviews on G2
| Need | Tool | Notes |
|---|---|---|
| Inbox provisioning and DNS | Inframail | Microsoft 365 inboxes, automated DNS |
| Campaign sending and warmup | Instantly | Connects via SMTP/IMAP, warmup built in |
| Verified contact data | Quarvio | Pre-verified, 90% deliverability guarantee |
| LinkedIn outreach | Aimfox | LinkedIn campaigns alongside email |
How long does Inframail setup take from start to first campaign?
The full setup takes 2–4 hours of active work, but the timeline to first campaign is longer due to warmup requirements. Active work includes: account creation (10 minutes), domain addition and DNS record copy (20 minutes), DNS propagation wait (15–60 minutes), inbox creation (30 minutes for 5–10 inboxes), Instantly connection (30 minutes), warmup activation (15 minutes), and pre-campaign verification (30 minutes). After that, the warmup period of 14–28 days must run before campaigns begin.
Can I use Inframail with Google Workspace instead of Microsoft 365?
Inframail provisions Microsoft 365 inboxes specifically. If you want Google Workspace inboxes, you would need to provision those separately through Google directly. Inframail's value proposition is the automated DNS configuration and flat-rate pricing for Microsoft 365 inboxes, which makes it specific to the Microsoft infrastructure stack.
How many inboxes should I create on one domain?
The recommended range is 3–5 inboxes per domain. This keeps the sending volume per inbox at sustainable levels (30–50 emails per day) without overloading the domain's reputation with too many concurrent sending addresses. For higher volume, add more domains rather than more inboxes per domain.
What is the difference between SMTP and IMAP, and why does Instantly need both?
SMTP (Simple Mail Transfer Protocol) is the outgoing mail protocol — Instantly uses your SMTP credentials to send cold emails from your Inframail inbox. IMAP (Internet Message Access Protocol) is the incoming mail protocol — Instantly uses your IMAP credentials to read reply emails, enabling reply detection and warmup engagement. Both are required for Instantly to function correctly.
Do I need to set up SPF, DKIM, and DMARC manually?
No. Inframail auto-generates the correct records for your Microsoft 365 inboxes when you add a domain. You copy the generated records and add them to your registrar's DNS panel. The records themselves are created by Inframail, not by you. The only manual step is copying them into your registrar's DNS interface.
What domains should I buy for cold email sending?
Never use your primary business domain for cold email. Purchase separate sending domains that are variations of your brand: meetyourcompany.com, teamyourcompany.com, getyourcompany.com. This protects your main domain's reputation. Sending domains take all the deliverability risk; if one gets blocklisted, your primary domain is unaffected. Buy at least 3 sending domains to start; add more as volume scales. Quarvio can help with contact strategy while you build your domain portfolio.
How do I know when warmup is complete?
Warmup is a continuous process, not a one-time event, but inboxes are ready for campaigns when: (1) they have been warming up for at least 14 days, (2) the warmup score in Instantly is trending upward, and (3) inbox placement tests show 70%+ inbox rate. These three signals together indicate sufficient reputation has been established for low-to-moderate campaign volume. Full maturity (suitable for 40–50 emails per day) typically takes 28–60 days.
Can I use Inframail inboxes with Smartlead instead of Instantly?
Yes. Inframail exports standard SMTP and IMAP credentials that work with any tool accepting SMTP connections: Instantly, Smartlead, Lemlist, Mailshake, and others. The connection process is the same regardless of the sending tool: enter SMTP settings for outbound, IMAP settings for inbound, and test the connection.
What happens if my Inframail inbox gets blocklisted?
Stop all sending from that inbox and domain immediately. Identify the specific blocklist through MXToolbox and submit a removal request. Investigate the root cause (typically high bounce rate or high complaint rate from the campaigns using that inbox). Fix the root cause before requesting removal — if the issue is still active when you resume, you will be re-listed. Run a more intensive warmup period after removal before resuming cold campaigns.
How does Inframail pricing compare to setting up Microsoft 365 directly?
Microsoft 365 Business Basic costs approximately $6 per user per month. At 10 inboxes, that is $60/month directly from Microsoft. Inframail's flat per-domain pricing (check current rates at inframail.io) is typically below this for small inbox counts and becomes significantly cheaper as inbox counts grow, because the flat fee does not increase with inbox count.
Place your contact order before launching campaigns
Clean inbox setup is half the deliverability equation. Clean contact data is the other half. Before launching cold campaigns from your newly configured Inframail inboxes, verify your contact list meets quality standards.
Quarvio delivers pre-verified B2B contacts at $129 for 5,000 contacts through $699 for 50,000 contacts. 90% deliverability guarantee, 12-month credit validity, unused credits carry forward.
Start your contact order at Quarvio →