GMX Mail SMTP settings: smtp.gmx.com, port 587
GMX outgoing mail server: smtp.gmx.com (smtp.gmx.net for gmx.de/gmx.net), port 587 STARTTLS or 465 SSL, full address and password — after enabling POP3/IMAP access in GMX settings.
GMX outgoing mail server:
smtp.gmx.com, port <code>587</code> (STARTTLS) or <code>465</code> (SSL/TLS), username = your full GMX address, password = your GMX password.
GMX SMTP settings at a glance
| Outgoing (SMTP) host | smtp.gmx.com (international) — smtp.gmx.net for German gmx.de / gmx.net accounts |
|---|---|
| Ports & encryption |
587 — STARTTLS465 — SSL/TLS |
| Username | your full GMX address |
| Password | your GMX password (GMX does not use app passwords, but external access must be switched on) |
| Authentication | GMX blocks SMTP until you enable it: Settings → POP3 & IMAP → "Enable access to this account via POP3 and IMAP". Two-factor accounts need an application password. |
How to set up GMX SMTP
- GMX web mail → Settings → POP3 & IMAP → enable external access → Save.
- App settings: host smtp.gmx.com (or smtp.gmx.net), port 587 STARTTLS, username = full address, password = account/application password.
Sending limits
- GMX allows about 100 recipients per hour on free accounts and may block for 24 h after bursts.
- From must be the GMX address or a verified alias.
Things that catch people out
- Using smtp.gmx.com for a gmx.de account (or vice versa) fails authentication.
Common GMX SMTP errors
| Server reply | Meaning | Fix |
|---|---|---|
535 Authentication credentials invalid | External access not enabled or wrong host for the domain. | Enable POP3/IMAP access and use the matching host. |
More codes: 535 authentication failed, 550 relay denied, 554 rejected as spam, connection timed out — or all SMTP error codes.
When GMX is not enough for your app
When a provider caps you or blocks a port, point the same app at QueenSMTP instead: host smtp.queensmtp.com, port 587 (STARTTLS) or 465 (SSL), your SMTP username and password from the dashboard. $5/year plus $0.10 per 1,000 emails, 100 free a day to test.
Get SMTP credentials — free to test Test GMX nowRelated settings
GMX SMTP — questions
smtp.gmx.com for international accounts (smtp.gmx.net for gmx.de/gmx.net), port 587 with STARTTLS or 465 with SSL, after enabling POP3/IMAP access in settings.
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