MailerLite SMTP Settings and Configuration (2026)
MailerLite does not provide native SMTP — use MailerSend instead
MailerLite is broadcast-only: newsletters and automations through its marketing UI, no SMTP endpoint for transactional traffic. For SMTP relay, MailerLite officially routes users to MailerSend — its companion transactional product, sharing single sign-on. MailerSend starts at 500 emails/month free and $5.60/mo for 5,000. The settings below apply to MailerSend only.
If you already run MailerLite for broadcasts and want a single vendor for transactional traffic (order confirmations, password resets, receipts), MailerSend is the intended path — SSO links the two accounts so you manage both from one login. If you only need SMTP relay and do not use MailerLite marketing, cheaper native-SMTP options exist: Brevo bundles SMTP into its Free plan (300 emails/day), and Amazon SES beats everyone on unit price if you can handle IAM setup. For developer-focused transactional with better logs and message streams, see Postmark.
Quick reference
The essential MailerSend SMTP settings, ready to copy-paste into your email client, WordPress plugin, or transactional integration.
| SMTP server | smtp.mailersend.net |
|---|---|
| SMTP port (STARTTLS) | 587 ONLY PORT |
| SMTP port (SSL/TLS) | Not supported |
| Alternative port | Not supported (no 465, no 2525) |
| TLS version | 1.2 or 1.3 required (1.0/1.1 deprecated) |
| Authentication | LOGIN (SMTP user credentials) |
| Username | Auto-generated SMTP username (from MailerSend dashboard) |
| Password | Auto-generated SMTP password (shown once at creation) |
SMTP configuration
Outgoing mail server
— sending email via MailerSend
Setup steps
- Sign up for MailerSend at
mailersend.com. If you already have a MailerLite account, use SSO to link the two — no separate login required. - Verify your sending domain under Domains › Add domain. Publish the SPF TXT, two DKIM CNAME records (
ms1._domainkeyandms2._domainkey), and the return-path CNAME. Wait for verification (typically minutes, up to 48h). - Open the domain’s Manage page, click the SMTP users tab, then Generate new SMTP user. Name it (e.g.
wordpress-transactional). - Copy the auto-generated username and password immediately — MailerSend shows the password only once.
- In your email client or WP SMTP plugin, enter host
smtp.mailersend.net, port 587, encryptionSTARTTLS, TLS version 1.2 or higher. - Username = the auto-generated SMTP user. Password = the auto-generated SMTP password from step 4.
- Send a test email. Check the Activity dashboard for delivery status, bounces, or auth errors.
Authentication
MailerSend uses LOGIN authentication with a dedicated per-domain SMTP user. The SMTP credential is not the same as your API token — API tokens power the HTTP Email API and have their own permission scopes. Pasting an API token as the SMTP password will fail with a 535 response.
- Per-domain SMTP users: each verified domain has its own SMTP user pool. Free/Trial/Hobby plans allow 1 SMTP user per domain; Starter allows 5; Professional/Enterprise allow 20.
- Single-transaction cap: MailerSend limits one SMTP connection to 5 messages per session. Close and reopen the connection for larger batches, or switch to the Bulk Email API.
- Concurrent connections: 5 on Trial/Free/Hobby/Starter plans, 50 on Professional/Enterprise. Exceeding the cap yields temporary connection failures.
- TLS enforcement: TLS 1.2 or 1.3 required. TLS 1.0 and 1.1 were deprecated on June 3, 2024 and no longer accepted.
Domain authentication (SPF, DKIM, return-path)
MailerSend requires you to verify and authenticate your sending domain before releasing traffic to real recipients. The wizard lives under Domains › Add domain and produces four DNS records to publish. Propagation typically completes in a few minutes, up to 48 hours worst case.
SPF record
MailerSend requires an SPF TXT record on your sending domain. If you already have an SPF record, merge the MailerSend include into it — never publish two separate v=spf1 records at the same DNS zone. The MailerSend value is provided in the setup wizard.
DKIM records (CNAME format)
MailerSend uses two DKIM CNAME records, at ms1._domainkey.yourdomain.com and ms2._domainkey.yourdomain.com. CNAME format lets MailerSend rotate 2048-bit keys transparently — no manual TXT update required down the line.
Return-path CNAME
MailerSend also requires a return-path CNAME (default host mta.yourdomain.com) pointing to mailersend.net. This enables bounce processing on a subdomain of your sending domain, which improves DMARC alignment.
DMARC alignment
DMARC is optional but strongly recommended, especially since Gmail, Yahoo, and Microsoft’s bulk-sender rules (in force since February 2024) effectively require it for volume senders. Because MailerSend signs with DKIM using your own domain (via the CNAME setup) and processes bounces via your return-path subdomain, DMARC alignment (both DKIM and SPF) is achieved cleanly. Publish a DMARC TXT at _dmarc.yourdomain.com starting with p=none for reporting, then tighten to p=quarantine or p=reject once you confirm alignment via reports.
Rate limits & sending caps
| Limit type | Value | Notes |
|---|---|---|
| Free plan monthly quota | 500 emails/month | Includes SMTP relay + Email API + drag-and-drop templates. |
| Free/Trial daily request cap | 100/day | Combined SMTP + API request ceiling on Free tier. |
| Hobby plan monthly quota | 5,000/month ($5.60/mo) | Monthly quota, no daily cap. 1 SMTP user per domain. |
| Starter plan monthly quota | 50,000/month | 5 SMTP users per domain. 5 concurrent connections. |
| Professional daily request cap | 500,000/day | 20 SMTP users per domain. 50 concurrent connections. |
| General SMTP throughput | ~120 requests/minute | Applied per IP. Rate-limited lower than the HTTP API — use the Bulk API for volume bursts. |
| Messages per SMTP connection | 5 | Single-transaction cap. Close and reopen the connection between batches. |
| Concurrent SMTP connections | 5 (Free–Starter) · 50 (Pro+) | Exceeding yields temporary connection failures. Contact support for higher. |
| Overage pricing | $0.90 per 1,000 emails | Applies once monthly quota is exhausted on Hobby+ plans. |
What happens at the limit: MailerSend defers new SMTP sessions with a temporary 4xx response when you hit the per-minute or concurrent-connection ceiling. Persistent daily overage on the Free plan pauses account sending until the next 24h window rolls over. Domain-level abuse (spam complaints, high bounce rate) triggers manual review — verified accounts with clean history rarely see this.
Common setup gotchas
Trying to use MailerLite credentials for SMTP
MailerLite has no SMTP endpoint. Your MailerLite email and password cannot authenticate against any SMTP server. You must create a MailerSend account (SSO from MailerLite is the fastest path) and generate an SMTP user under a verified domain there.
Using an API token as the SMTP password
MailerSend has two credential systems: API tokens for the HTTP Email API, and SMTP users for the SMTP relay. They are not interchangeable. Pasting an API token into an SMTP password field returns 535 authentication failed. Generate a dedicated SMTP user under Domains › Manage › SMTP users.
Assuming port 465 or 2525 works
MailerSend supports only port 587 with STARTTLS. There is no implicit SSL/TLS on 465 and no 2525 fallback. If your firewall blocks 587 outbound (rare on modern hosts, more common on legacy shared hosting), switch to the MailerSend HTTP Email API or move to a provider that supports 2525 like Brevo.
Missing the single-connection 5-message cap
MailerSend closes SMTP sessions after 5 messages. If your app opens one long-lived connection and pushes hundreds of messages, you will see silent drops or 421 responses after the fifth message. Configure your mail library to reconnect between batches or use the Bulk Email API for volume.
TLS 1.0/1.1 clients are rejected since June 2024
MailerSend requires TLS 1.2 or 1.3. Legacy WordPress installs on old PHP versions (< 7.4) or ancient mail libraries may still default to TLS 1.0 or 1.1 — those handshakes now fail. Update PHP and your SMTP library before pointing at MailerSend.
Migrating SMTP setups
To MailerSend (from another provider)
Update your app’s SMTP config to smtp.mailersend.net:587 with STARTTLS, swap credentials for a fresh MailerSend SMTP user, and keep the old provider active for 24 hours during DNS propagation. MailerSend applies conservative reputation limits to new domains — warm up gradually rather than firing your full list on day one. If you were previously sending via API on the old provider, budget time to test the SMTP client library thoroughly — the 5-message-per-session cap catches most apps off guard.
From MailerSend (to a cheaper or higher-volume alternative)
Brevo and Postmark are the most common destinations. Brevo undercuts MailerSend at low volume (300/day free vs 500/month) and supports ports 465 and 2525 for tricky firewalls. Postmark costs more but wins on developer ergonomics (message streams, richer webhooks, better logs). For high volume at bottom prices, Amazon SES beats everyone at ~$0.10 per 1,000 emails but demands IAM setup and your own IP warmup. Plan for 2 to 3 hours to reconfigure DNS, swap credentials, and verify deliverability.
Frequently asked questions
Can I use MailerLite for SMTP?
No. MailerLite is broadcast-only — newsletters and automations via its marketing UI, no SMTP endpoint. For SMTP-based transactional traffic (order confirmations, password resets, receipts, app notifications), MailerLite routes you to MailerSend, its companion transactional service. Use SSO to link the two accounts and manage both from one login.
What is the MailerSend SMTP server hostname and port?
Host: smtp.mailersend.net. Port: 587 with STARTTLS — and only 587. MailerSend does not offer 465 (implicit SSL/TLS) or 2525 (fallback). TLS 1.2 or 1.3 is required.
What credentials do I use for MailerSend SMTP?
You need an SMTP user, not an API token. Create one under Domains › Manage › SMTP users › Generate new SMTP user. MailerSend auto-generates both the username and password — copy the password immediately, it is shown only once. Pasting an API token as the SMTP password will fail with 535 authentication failed.
How many emails can I send per month on the MailerSend Free plan?
500 emails per month on the Free plan, with a hard cap of 100 combined SMTP + API requests per day. Hobby ($5.60/mo) lifts the daily cap and raises the monthly quota to 5,000. Starter goes to 50,000/mo, Professional to 500,000/day.
Does MailerSend require SPF, DKIM, and DMARC?
SPF and DKIM are required before MailerSend releases traffic to real recipients. DKIM is set as two CNAME records (ms1._domainkey and ms2._domainkey) pointing at MailerSend, which lets MailerSend rotate 2048-bit keys transparently. A return-path CNAME (default mta.yourdomain.com) is also required. DMARC is optional but strongly recommended given Gmail/Yahoo/Microsoft bulk-sender rules in force since February 2024.
What is the 5-message-per-connection limit?
MailerSend closes an SMTP session after 5 messages. Send a sixth message on the same connection and you get a 421 response. Configure your mail library to reconnect between batches, keep sends under 5 per session, or switch to the MailerSend Bulk Email API for higher-throughput scenarios.
Can I test the MailerSend SMTP connection from the command line?
Yes. Example with swaks:
swaks --to test@yourdomain.com --server smtp.mailersend.net --port 587 --auth LOGIN --auth-user MS_XXXXXX@yourdomain.com --auth-password YOUR_SMTP_PASSWORD --tls
A 250 OK confirms authentication and TLS negotiation. If you see 535, the credential is wrong (likely an API token instead of an SMTP user password). If you see 421 after 5 messages, that is the single-connection cap — reconnect.
Does MailerSend support IMAP or POP3?
No. MailerSend (like every email service provider) is outbound-only. It sends your emails to recipients but does not host an inbox for you to read via IMAP or POP3. Those protocols are for mailbox providers like Gmail, Yahoo, or your ISP. See our email settings cluster for IMAP/POP3 configuration by mailbox provider.
This review follows our email infrastructure testing methodology. We disclose affiliate relationships in our editorial independence policy.
