Email server settings
Mailgun SMTP settings
The Mailgun SMTP settings are smtp.mailgun.org for domains in the US region or smtp.eu.mailgun.org for the EU region, port 587 with STARTTLS (or 465 with TLS), and the SMTP credentials of the domain you send from. Every sending domain has its own SMTP login and password.
Last checked October 10, 2026, against Mailgun’s own documentation.
Mailgun SMTP servers and ports
| Server, port and securityServer | Port and security |
|---|---|
| SMTP · outgoingsmtp | 587, 2525, 25STARTTLS |
| SMTP · outgoingsmtp | 465SSL/TLS |
| SMTP · outgoingsmtp | 587, 2525, 25STARTTLS |
| SMTP · outgoingsmtp | 465SSL/TLS |
Sign-in: Domain SMTP credentials
User name: the SMTP credentials of the sending domain, from Domain settings → SMTP credentials in the Mailgun control panel. Each domain has its own.
Mailgun SMTP settings explained
- Pick the host by region. Mailgun’s API overview lists
smtp.mailgun.orgas the outgoing SMTP server for the US region andsmtp.eu.mailgun.orgfor the EU region, and tells you to use the endpoints of the region where you created the domain. - Ports (Sending messages via SMTP): Mailgun listens on 25, 465, 587 and 2525. Port 465 requires TLS from the start; 25, 587 and 2525 start without TLS and can be upgraded with
STARTTLS. - Use 587. “Some ISPs are blocking or throttling SMTP port 25. Using port 587 is recommended.”
- Use the host name, not IPs. Mailgun’s IP addresses “will change frequently and be subjected to change without notice”.
- Addresses must parse. Addresses that fail Mailgun’s syntax check end in a “Cannot parse to address” or “cannot parse from address” error.
Per-domain SMTP credentials
SMTP credentials belong to a domain, not to your account: “Your SMTP credentials are different for each domain you add” (Mailgun Help).
- In the control panel, go to Send → Sending → Domain settings and open the SMTP credentials tab.
- Check that the right domain is selected in the domain drop-down in the upper right corner.
- Use an existing SMTP login, or click Reset password and confirm. Copy the new password into your app and a password manager; Mailgun doesn’t display it again.
Credentials can also be managed through Mailgun’s HTTP API.
Sandbox domain and authorized recipients
Every new Mailgun account gets a sandbox domain, which is “for testing purposes only” and “can only send to authorized recipients” (Mailgun docs). Add up to 5 on the Setup tab of the sandbox domain’s settings; each one becomes “Verified” after the person clicks the activation link (Authorized Recipients).
For real mail, add your own sending domain in Mailgun and complete its DNS setup (background: SPF record, DKIM record). Then use that domain’s SMTP credentials with the host for its region.
Common Mailgun SMTP problems
| Error or symptom | Fix |
|---|---|
| Login fails although the password is right | The credentials belong to another domain, or the host doesn’t match the domain’s region. Use the SMTP login of the sending domain with smtp.mailgun.org (US) or smtp (EU). |
| Timeouts on port 25 | Some ISPs block or throttle port 25. Use 587 with STARTTLS, or 2525. |
| “Cannot parse to address” / “cannot parse from address” | An address failed Mailgun’s syntax check. Fix the address format; email address format lists the rules. |
| Sandbox mail only reaches some recipients | Sandbox domains send only to authorized recipients (up to 5). Add and verify the recipient, or send from your own domain. |
Bounce codes from receiving servers are explained in the SMTP error codes reference. Many hard bounces hurt your sending reputation, so clean a list with the bulk email verifier before the first send.
Sources
Checked on October 10, 2026. Server names, ports and sign-in rules come from these official pages:
Other SMTP relay services
Mailgun SMTP settings: FAQ
What are the Mailgun SMTP settings?
smtp.mailgun.org (US) or smtp.eu.mailgun.org (EU), port 587 with STARTTLS or 465 with TLS (25 and 2525 also work), and the SMTP login and password of your sending domain.What is the Mailgun SMTP server for the EU?
smtp.eu.mailgun.org. Use it for domains created in the EU region; domains in the US region use smtp.mailgun.org.Where do I find my Mailgun SMTP password?
Which port should I use for Mailgun SMTP?
Email validation API
Validate recipients before you send through Mailgun
emailvalidation.io checks syntax, MX records and the mailbox over SMTP, flags disposable, role and free addresses and returns a quality score, in one request.
/v1/info Email validation API Read the documentation
100 free validations every month. No credit card required.
GET https://api.emailvalidation.io/v1/info?
{
"email": "support@emailvalidation.io",
"user": "support",
"tag": "",
"domain": "emailvalidation.io",
"format_valid": true,
"mx_found": true,
"smtp_check": true,
"catch_all": null,
"role": true,
"disposable": false,
"free": false,
"score": 0.64,
"state": "deliverable",
"reason": "valid_mailbox",
"did_you_mean": ""
}