Custom SMTP
Connect custom SMTP to EonMailer
Host, port, TLS, and credentials for any SMTP relay.
Step 1 — Gather SMTP details from client IT
| Field | Example |
|---|---|
| Host | smtp.client.com |
| Port | 587 (STARTTLS) or 465 (SSL) |
| Username | eonmailer@client.com |
| Password | app-specific password |
| Auth method | PLAIN/LOGIN |
Warning Never use personal mailbox passwords — request a dedicated relay account with send-only scope.
Step 2 — Configure in EonMailer
- Client workspace → Settings → Email provider → Custom SMTP.
- Enter host, port, encryption (STARTTLS recommended on 587).
- Username/password.
- Optional: custom HELO/EHLO name if relay requires it.
- Test connection.
Step 3 — Domain verification
SMTP doesn’t replace DNS auth. Add sending domain in EonMailer and publish SPF/DKIM per relay docs — many relays sign DKIM themselves; still add SPF include client IT provides.
Step 4 — Send limits
Ask IT for hourly/daily caps. Schedule large broadcasts below cap or request temporary increase.
Step 5 — Test
Send to external Gmail/Outlook; verify headers show pass for SPF/DKIM if relay signs.
Troubleshoot SMTP on failure.