Connect MailerSend
Modern and developer-friendly. Note: no port 465 — use 587.
MailerSend is a modern provider with a clean dashboard. One thing to know up front: it does not support port 465 — use 587.
SMTP settings at a glance
| Setting | Value |
|---|---|
| Server | smtp.mailersend.net |
| Ports | 587 (STARTTLS, recommended) · 2525 (fallback) |
| Username | Auto-generated per domain (Step 2) |
| Password | Auto-generated per domain (Step 2) |
⚠️ There is no port 465 on MailerSend. Use 587, or 2525 if 587 is blocked.
Step 1 — Add & verify your domain
- In MailerSend: Domains → Add domain.
- Add the SPF (TXT), DKIM (CNAME), and Return-Path (CNAME) records shown, then Finish verification.
New/trial accounts are limited (a trial domain can only email a couple of approved addresses) until your account is approved — submitting your company details speeds this up.
Step 2 — Generate SMTP credentials
- Domains → click Manage on your domain → scroll to the SMTP section.
- Click Generate new user, name it, Save. A username and password are created (case-sensitive).
Step 3 — Paste into Mailbo
- Settings → SMTP & sending → click the MailerSend tile.
- Sender: From email (any address on your verified domain) + From name.
- Credentials: the generated username and password. Use port 587.
- Save, then Send test email.
Troubleshooting
| Problem | Fix |
|---|---|
| Won't connect on 465 | MailerSend doesn't support 465 — switch to 587. |
| Sends limited / blocked | Your account may be unapproved (1 CC + 1 BCC limit) — complete approval. |
| Auth fails | Credentials are case-sensitive; the username is not your From address. |
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Last updated 6/15/2026← More in Sending & Deliverability