How Lemlist + ColdRelay Work Together
ColdRelay (Infrastructure)
ColdRelay provides the mailboxes Lemlist sends from. Each mailbox is a Microsoft 365 account on a dedicated, isolated Azure tenant with its own dedicated IP, fully-automated DNS (SPF, DKIM, DMARC), and a 95% inbox-placement guarantee. ColdRelay's pricing is per-mailbox: $1 (1-199), $0.85 (200-999), $0.70 (1K-4,999), $0.55 (5K+). Setup completes in 60 minutes, no warmup wait.
Lemlist (Sending Platform)
Lemlist is a sales engagement platform known for personalization at scale — custom images, video personalization, conditional handlebars, and multi-channel sequences that combine email with LinkedIn touches and cold calls. Lemlist orchestrates the campaign logic, reply detection, and per-prospect personalization tokens. Lemlist does NOT provide the underlying email infrastructure. You bring your own mailboxes via SMTP/IMAP credentials (or use connected Google / Microsoft mailboxes), and Lemlist sends through them.
Why use them together
Lemlist is the brain (sequences, personalization, multi-channel orchestration). ColdRelay is the body (mailboxes, IPs, DNS). Lemlist's strength is per-prospect personalization — custom images with the prospect's name, conditional copy blocks, LinkedIn + email blended cadences — and that strength is amplified when the underlying infrastructure isn't the bottleneck on deliverability. The combination gives you premium personalization on premium infrastructure. Switching either side later is straightforward because they're loosely coupled.
Connect Lemlist to ColdRelay (Step-by-Step)
- 1
Order ColdRelay mailboxes
Sign up at coldrelay.com/sign-up, pick a domain (ColdRelay handles registration for $14), and order your mailbox count. The minimum is 50 mailboxes ($50/month at the base tier). ColdRelay's automation provisions the dedicated mail server, registers the domain, and creates all mailboxes inside an isolated Azure tenant.
Note: Provisioning takes 60 minutes end-to-end. You'll receive a CSV with every mailbox's SMTP host, port, username, and password once it's complete.
- 2
Wait for DNS propagation
ColdRelay configures SPF, DKIM, and DMARC records automatically on the new domain. DNS propagation usually completes in under an hour but can take up to 24. You can verify with the Email Deliverability Test at coldrelay.com/tools/email-deliverability-test — when SPF, DKIM, DMARC, and MX all show as configured, you're ready.
Note: Don't start sending before all four records (SPF, DKIM, DMARC, MX) verify correctly. Sending before authentication is in place causes immediate spam-folder placement and burns the domain reputation before you've sent a single real campaign.
- 3
Connect mailboxes to Lemlist
In Lemlist, go to Settings → Senders → Add a sender → Custom SMTP. For each ColdRelay mailbox, paste its SMTP host (box.YOURDOMAIN.com), SMTP port (587), SMTP username (the full email address), and the password from the ColdRelay CSV. Repeat for IMAP using port 993. Lemlist tests the connection and marks the sender as Connected once it validates.
Note: Lemlist supports both OAuth (for Google / Microsoft consumer accounts) and Custom SMTP. ColdRelay mailboxes use the Custom SMTP path — there is no OAuth flow because the mailboxes sit on your isolated Azure tenant, not a consumer Microsoft 365 / Google Workspace tenant.
- 4
Set daily limits per sender
In each Lemlist sender's settings, set the daily send limit to 2 outbound emails per day. This matches ColdRelay's per-mailbox cap (designed for optimal deliverability, not maximum volume). With 50 mailboxes you can send 100 outbound emails/day; 200 mailboxes = 400/day; 1,000 mailboxes = 2,000/day.
Note: Going higher than 2/day/mailbox is the single fastest way to degrade deliverability. ColdRelay's pricing model assumes 2/day — if you need 5,000+ emails/day, add more mailboxes, don't push existing ones harder.
- 5
Enable warmup
Lemlist's built-in warmup product (Lemwarm) ramps mailbox reputation by exchanging emails with other senders in the Lemwarm network. Enable it per sender from the Lemwarm tab. Set the daily warmup limit to 2 emails to match ColdRelay's combined 4/day total (2 outbound + 2 warmup) cap. Warmup ramps the mailbox over the first 2 weeks.
Note: Lemwarm is bundled with Lemlist's Email Pro and higher tiers, and also sold standalone. ColdRelay mailboxes ship reputation-ready (the dedicated Azure tenant + dedicated IP gives you a clean start) but warmup is still recommended for the first 2 weeks of active sending.
- 6
Build the campaign with personalization
In Lemlist, create a campaign, upload your prospect list, and write the sequence. Lemlist's superpower is personalization tokens — use {{firstName}}, custom images with the prospect's company logo overlaid, conditional handlebars ({{#if industry == 'SaaS'}}...{{/if}}), and video personalization. Assign your ColdRelay senders to the campaign so sends rotate across all of them respecting each sender's daily cap.
Note: Lemlist's personalization quality is what justifies the higher per-seat cost compared to bare-bones senders. Lean into it — a generic Lemlist campaign wastes the tool. Use the Spintax Generator at coldrelay.com/tools/spintax-generator for subject-line variation on top of token personalization.
- 7
Add LinkedIn and call steps if multi-channel
If you're on Lemlist's Multi-channel plan, layer LinkedIn visits, connection requests, and cold-call reminders into the same sequence. The email steps still flow through your ColdRelay senders; the LinkedIn steps require connecting the operator's LinkedIn account. Multi-channel cadences typically lift reply rates 20-40% vs email-only.
Note: Multi-channel doesn't change anything about how ColdRelay's mailboxes work — the email steps are still SMTP-only. ColdRelay has no involvement in the LinkedIn / call legs.
- 8
Monitor deliverability ongoing
Run the Email Deliverability Test weekly to verify SPF/DKIM/DMARC stay passing. Check Google Postmaster Tools for spam-folder rates and IP reputation. ColdRelay automatically monitors blocklists — you'll get an alert if any of your dedicated IPs hit a major blocklist (Spamhaus, Barracuda, SORBS, SpamCop).
Note: ColdRelay's 95% inbox-placement guarantee is contingent on following the 2/day/mailbox cap. Exceeding the cap voids the guarantee.
Key Considerations for Lemlist + ColdRelay
Daily send limits per mailbox
Set Lemlist's per-sender daily limit to 2 outbound + 2 warmup = 4 total/day MAX. This is ColdRelay's optimal-deliverability cap. Going higher is the single biggest cause of mailbox burnout we see. Scale total volume by adding more mailboxes, not by pushing existing ones harder. Lemlist makes the cap easy to enforce — it surfaces a clear daily-limit field per sender.
Dedicated IPs end shared-IP risk
Each ColdRelay mailbox is on a dedicated IP within your isolated Azure tenant. Other Lemlist users sending from shared infrastructure are sharing IP reputation with random other senders — bad actors on the same IP damage everyone's deliverability. With ColdRelay your IP reputation is entirely your own, which matters even more when you're running highly personalized campaigns that you want hitting the inbox cleanly.
Personalization features don't change infrastructure requirements
Lemlist's custom images, video personalization, and conditional handlebars all happen at the application layer before the SMTP send. The actual email leaving your ColdRelay mailbox is just a standard MIME message — slightly larger if it contains an inline custom image, but still a normal email. No special ColdRelay configuration needed for any Lemlist personalization feature.
Lemwarm vs ColdRelay's own warmup
Lemwarm is Lemlist's warmup network. ColdRelay does not run a competing warmup network — we rely on the sending platform's warmup or third-party warmup tools. Use Lemwarm if you're already on a Lemlist plan that includes it; otherwise turn on whatever warmup your plan offers. The combined cap (4/day inclusive of warmup) stays the same.
Switching cost is low
If you decide Lemlist isn't right and want to switch to Instantly, Smartlead, or another sender later, your ColdRelay mailboxes work with any platform that supports custom SMTP/IMAP. You don't lose the infrastructure investment. The harder switch is on the Lemlist side — porting personalization tokens and custom-image templates to a less-featured platform is the part that hurts.
Domain-rotation strategy
ColdRelay caps each domain at 100-150 mailboxes for deliverability reasons. If you need 500+ mailboxes, you'll order multiple domains. Lemlist handles multi-domain campaigns natively — assign senders from each domain to different campaign tracks to spread risk. This is especially important with Lemlist where the high personalization makes each campaign more valuable to keep clean.
Pricing Snapshot
ColdRelay
ColdRelay's per-mailbox cost ranges from $1.00 (1-199 mailboxes) down to $0.55 (5,000+). Domain registration is $14/year, one-time. For 200 mailboxes: 200 × $0.85 = $170/month + $14 annual domain cost.
Lemlist
Lemlist's pricing is per-seat. Their Email Starter plan runs roughly $59/user/month, Email Pro (which bundles Lemwarm warmup and more personalization features) runs roughly $99/user/month, and the Multi-channel plan (email + LinkedIn + cold call workflows) runs roughly $159/user/month. Pricing scales with the number of operators using the platform, not the number of mailboxes or emails. Check lemlist.com for current pricing.
Total monthly
A typical 200-mailbox cold email operation with 2 operators: ColdRelay infrastructure at ~$170/month + Lemlist Email Pro at ~$198/month (2 seats) = ~$368/month total. At 1,000 mailboxes with 3 operators on Multi-channel: ColdRelay $700/month + Lemlist ~$477/month = ~$1,177/month. Compare against Google Workspace at $6+/mailbox/month: 200 GW mailboxes alone would be $1,200/month before Lemlist's per-seat cost.
Common Issues + Fixes
⚠ Sender stuck in 'Connecting' or fails connection test in Lemlist
Lemlist's SMTP test checks both auth and a test send. The most common cause is the password being copied with a trailing space from the ColdRelay CSV — re-paste carefully. Second most common: SMTP port set to 465 (SSL) instead of 587 (STARTTLS). ColdRelay mailboxes accept both, but Lemlist's default Custom SMTP flow expects 587. If both look right, regenerate the mailbox password from the ColdRelay dashboard and re-enter it.
⚠ Custom-image personalization renders but lands in spam at Gmail
Inline custom images add to message size and to spam-filter scrutiny. Run the Email Deliverability Test against the domain. If SPF, DKIM, or DMARC fails, the records may not have propagated yet — wait 24 hours. If they all pass, the issue is usually content rather than infrastructure: image-heavy messages with thin text are flagged. Balance image personalization with substantive text. The Subject Line Generator at coldrelay.com/tools/subject-line-generator and CAN-SPAM Checker at coldrelay.com/tools/can-spam-checker can validate copy.
⚠ Inbox-placement test (Mail-Tester, GlockApps) shows missing DKIM
ColdRelay's DKIM is on the domain's _dkim.YOURDOMAIN.com selector. If a test reports missing DKIM, it usually means the test ran before DNS propagation completed. Wait 24 hours from provisioning and re-test. If still missing, contact ColdRelay support — there's a deliverability consultant included at higher mailbox volumes.
⚠ Replies not appearing in Lemlist's reply dashboard
Lemlist polls IMAP on port 993 with TLS. Verify the IMAP credentials match the ColdRelay CSV. Most commonly: the IMAP password is the same as the SMTP password but it can drift if a mailbox was reset. Re-test in Lemlist's sender settings (Test Connection button). If a reply lands in the mailbox but never surfaces in Lemlist, the message-ID matching may have missed — Lemlist's reply detection relies on threading headers, and aggressive forwarding rules can break the chain.
⚠ Lemwarm warmup not ramping the way it should
Lemwarm has its own status indicator per sender. If warmup is enabled but the daily count stays at zero, the most common cause is the sender being paused at the Lemlist account level (separate from the campaign-level pause). Check Settings → Senders for a paused state. Less commonly, the IMAP folder structure on the mailbox isn't standard — Lemwarm expects an INBOX folder; if a mail rule has moved warmup emails elsewhere, reset the rule.
Frequently Asked Questions
Do I need ColdRelay if I already have Lemlist?
Lemlist is a sending and engagement platform — it doesn't provide mailboxes or DNS. You need an infrastructure provider (ColdRelay, Google Workspace, etc.) underneath it. Most Lemlist users start with Google Workspace mailboxes ($6+/mailbox/month) and switch to ColdRelay because the infrastructure is purpose-built for cold email at a fraction of the cost ($0.55-$1.00/mailbox).
Is ColdRelay better than Google Workspace for use with Lemlist?
For cold email at any scale beyond a handful of mailboxes: yes. Google Workspace charges $6+/mailbox/month and shares some risk across all GW senders. ColdRelay charges $0.55-$1.00/mailbox/month, gives each customer a dedicated Azure tenant with dedicated IPs, and bakes SPF/DKIM/DMARC automation into provisioning. The infrastructure quality is closer to enterprise-grade at indie-tool prices — which pairs especially well with Lemlist's premium personalization features.
How many mailboxes do I need to scale to my target send volume on Lemlist?
ColdRelay's per-mailbox cap is 2 outbound emails/day for optimal deliverability. So if you want to send 1,000 emails/day through Lemlist, you need 500 mailboxes. The Mailbox Calculator at coldrelay.com/tools/mailbox-calculator lets you input your target volume and gives you the exact mailbox count + pricing tier. Lemlist itself doesn't cap volume — the cap is on the infrastructure side.
Does ColdRelay work with Lemlist's multi-channel sequences (LinkedIn + email)?
Yes. ColdRelay only touches the email leg of any multi-channel sequence — the LinkedIn and cold-call legs run inside Lemlist using the operator's own LinkedIn account and call setup. ColdRelay senders rotate through email steps exactly the same way they would in an email-only Lemlist campaign. Multi-channel typically lifts reply rates 20-40% vs email-only, so combining it with high-quality infrastructure is a strong fit.
Should I use Lemwarm or skip warmup with ColdRelay?
Use Lemwarm (or any warmup) for the first 2 weeks of active sending. ColdRelay mailboxes ship reputation-ready because the Azure tenant and dedicated IP isolation give a clean starting point, but warmup still helps establish positive engagement signals before campaigns ramp. Keep the combined cap at 4/day (2 outbound + 2 warmup) — going higher to 'warmup faster' damages reputation.
Will my Lemlist campaigns break if I switch to ColdRelay from another provider?
No. Switching infrastructure providers mid-campaign requires reconnecting each sender in Lemlist (new SMTP/IMAP credentials), but campaign logic, personalization templates, custom images, conditional handlebars, and prospect lists all stay intact. The transition takes a few minutes per sender. We recommend pausing campaigns during the swap to avoid any deliverability blips.
What if Lemlist's deliverability is bad with my ColdRelay mailboxes?
That's almost always a campaign-content issue (overly heavy image personalization, subject lines triggering spam filters, link density too high) rather than an infrastructure issue. ColdRelay's 95% inbox guarantee means the infrastructure is doing its job. Use the CAN-SPAM Checker at coldrelay.com/tools/can-spam-checker and the Subject Line Generator to validate campaign content. ColdRelay's deliverability consultant (included at higher volumes) can help diagnose specifically what's tripping spam filters in a Lemlist setup.