GMX Server Settings: IMAP, SMTP and POP3

Everything needed to connect GMX to a mail client, in one place. GMX is unusual in one important respect: correct settings alone are not enough. There is a switch you have to turn on first — and GMX may turn it back off later without telling you.

Turn on external access first

GMX deactivates POP3 and IMAP by default. Until you enable it, no mail program can connect no matter how correct your settings and password are, and the error you get says "authentication failed" — which sends almost everyone hunting for a password problem that does not exist.

1. Sign in to GMX in a browser.

2. Open the Email tab and click Settings.

3. Click POP3 & IMAP.

4. Tick Enable access to this account via POP3 and IMAP.

5. Click Save.

GMX may switch it off again

This is the part worth remembering, because it explains a failure that otherwise makes no sense.

GMX states that this setting is turned off automatically, for security reasons, if you do not use POP3 or IMAP for a longer period.

So a setup that worked perfectly for months can simply stop, with nothing changed at either end and no notification. The symptom is an authentication error from a mail program whose settings are still entirely correct.

If that describes your situation — it worked, nothing changed, now it does not — check this switch before touching anything else. Re-ticking it is often the whole fix.

GMX server settings

Your username is your full email address. Authentication is required on the outgoing server as well as the incoming one.

Port 465 with SSL also works for outgoing mail, and is worth trying if 587 will not connect — some networks block one and not the other.

German gmx.net accounts

If your address ends in gmx.net rather than gmx.com, use the gmx.net hostnames instead — imap.gmx.net and mail.gmx.net. Same service, different servers, and using the wrong pair produces a failure that looks exactly like wrong credentials.

If your program does not offer STARTTLS

GMX's own guidance: if STARTTLS is not available, use TLS. If neither option exists, simply activating the program's "Encryption" option is sufficient.

One firm requirement: your program must support TLS 1.2 or 1.3. GMX no longer supports the older 1.0 and 1.1 for security reasons. A program too old to speak the newer versions cannot connect at all — and it will report that as a credentials failure rather than a protocol one.

IMAP or POP3?

Choose IMAP unless you have a specific reason not to.

IMAP synchronises. Your mail stays on GMX's servers and every device sees the same mailbox — read something on your phone and it shows as read on your laptop, move it to a folder and it moves everywhere.

POP3 downloads, and by default removes the server copy. That suits one narrow case — archiving mail permanently onto a single machine — and causes lasting confusion on any account used from more than one device.

There is also a GMX-specific reason to prefer IMAP, or at least to keep server copies when using POP3. GMX’s personal spam filter can be trained through GMX webmail and the official GMX Mail app, but not through third-party clients such as Outlook or Thunderbird.

If POP3 downloads and removes a misfiled message from the server, it will no longer be available in GMX’s official interfaces for correction. Configure the program to leave copies on the server so you can mark messages as Spam or Not Spam through GMX webmail or the official GMX Mail app.

Two things to configure in your program

Folder mapping

Many email programs cannot correctly match their own folders to GMX's system folders — a program's "Trash" may not line up with what GMX calls it — so the program creates its own instead, and your mailbox sprouts duplicates.

Set the mapping manually in your program's account settings so Sent, Drafts, Trash and Spam point at GMX's existing folders. Doing it once at setup avoids a mess that gets harder to untangle later.

Outgoing authentication

Tick "my outgoing server requires authentication" if your program has that option. GMX no longer supports the old SMTP-after-POP method, which allowed sending without authenticating — so a program relying on it will receive mail perfectly and fail to send.

If two-factor authentication is on

Your normal GMX password will not work in an external mail program after two-factor authentication is enabled. Create an application-specific password and use it for the mail account. GMX does not document a requirement for separate passwords for IMAP and SMTP.

A separate application-specific password may be needed when connecting another application or a different service, such as GMX Calendar or Contacts. See our GMX Security guide for setup instructions.

Sending limits

GMX uses automated anti-spam controls and does not publish one fixed sending threshold. Bulk or suspicious sending can cause messages to be rejected or the account to be blocked.

If GMX displays a warning or block, stop repeatedly retrying and sign in through GMX webmail to read the complete message and follow its instructions. Use a dedicated email-delivery service for newsletters, automated alerts or website-generated messages instead of a personal GMX mailbox.

If it still will not connect

• Is external access enabled? And has it been switched off automatically since you last used it?

• Right hostnames for your domain? gmx.com and gmx.net use different servers.

• Port and encryption matched? 993 with SSL, 995 with SSL, 587 with STARTTLS, 465 with SSL.

• Username is the full address? Not just the part before the @.

• App password, if 2FA is on? Your normal password will be refused.

• Program supports TLS 1.2 or 1.3? Older software cannot connect at all.

• Security software interfering? Antivirus and firewall mail scanning can block the connection silently.

And GMX's own best advice when an error makes no sense: sign in on the website on a computer. Some errors, such as temporary blocks, cannot be displayed properly by a mail program — the real message and its instructions appear there.