We’re tracking elevated error rates on IMAP and SMTP connections, plus sporadic delays in folder updates. The web client loads, but some users see empty inbox or repeated re-auth prompts. Mobile apps (iOS/Android) are the most affected, especially on cellular networks.
Quick takeaways
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- Try webmail first to confirm account health; if it loads, the issue is client-side or transport-related.
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- Toggle airplane mode, switch between Wi‑Fi and cellular, and flush DNS to bypass routing hiccups.
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- Re-enter credentials carefully; disable app-specific passwords temporarily and recreate if needed.
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- Update or reinstall your mail app; clear app cache/storage before re-adding the account.
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- Check GMX Email Status and community reports to confirm regional impact.
What’s New and Why It Matters
As of 2026, GMX has been migrating more authentication paths to modern OAuth-based flows while maintaining legacy IMAP/SMTP support. That change, plus stricter device trust checks, introduces new failure modes when a client or network doesn’t meet the updated handshake requirements. Today’s spike in GMX Störung reports reflects that shift: accounts are fine, but connections aren’t meeting the new criteria.
Why this matters: if your device or app is outdated, or your network path introduces latency, the new auth flow times out. That looks like a password error, but it isn’t. The result is login loops, sync stalls, and certificate warnings that resolve only after you modernize the client or adjust network settings.
Two things to watch. First, IMAP IDLE (push) can break when the server tightens keep-alive windows, causing “stuck” inboxes. Second, DNS-based filtering on some ISPs interferes with the SNI handshake for mail servers, producing intermittent “host unreachable” errors. Both are consistent with today’s reports and explain why switching networks or DNS often fixes things immediately.
Finally, some third‑party apps still rely on basic auth. GMX has been tightening this, so those apps get blocked even with correct passwords. If you’ve just started seeing failures after an app update or a policy change, this is likely the trigger.
Key Details (Specs, Features, Changes)
Compared to previous years, GMX’s 2026 authentication posture is stricter. Client TLS requirements are higher, server name indication (SNI) is enforced, and idle timeouts are shorter. The web client now revalidates sessions more aggressively, which can log you out if your device clock drifts or if you switch networks mid-session.
What changed vs before:
Legacy IMAP connections using only username/password are now subject to additional checks. Devices that can’t present a modern TLS stack or that don’t respect the new keep-alive window get dropped. Previously, many apps stayed connected for hours; now, the server terminates idle connections sooner to prevent resource hogging. That’s why some users see “sync stopped” on phones overnight.
IMAP IDLE behavior has been tuned. Push notifications may be delayed by a few minutes if the client heartbeats are too long. If your app pings every 10 minutes but the server expects a refresh every 3–5 minutes, the connection closes. Re-auth is required to resume sync, which looks like a login error to the end user.
SMTP routing also changed. Some regions now route through new gateway clusters. If your DNS cache points to old IPs, you’ll get connection refused or TLS handshake failures. Flushing DNS and switching to a trusted resolver (e.g., 1.1.1.1 or 8.8.8.8) typically resolves this.
Finally, device trust checks are more granular. If you recently updated your OS or browser, you may need to reconfirm the device in GMX’s security settings. This is not a bug; it’s an anti-hijacking measure. The side effect is a temporary login block until you approve the new device fingerprint.
How to Use It (Step-by-Step)
Follow this sequence to isolate and fix the issue. Start with the least invasive steps and escalate only if the problem persists.
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- Confirm account status via webmail: Open GMX in a browser and sign in. If inbox loads, your account is healthy. If not, reset your password and check for security prompts. While you’re there, glance at GMX Email Status to see if others are reporting similar issues.
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- Switch networks: Toggle airplane mode for 10 seconds, then reconnect. If on Wi‑Fi, try cellular or a different Wi‑Fi. This rules out ISP-level DNS or routing problems that often trigger GMX Störung symptoms.
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- Flush DNS and change resolver: On Windows, run
ipconfig /flushdns. On macOS,sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder. On Linux,sudo systemd-resolve --flush-caches. Then set DNS to 1.1.1.1 or 8.8.8.8 and retry.
- Flush DNS and change resolver: On Windows, run
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- Update your mail app: Outdated apps often fail the new TLS or SNI checks. Update from the official store. If the issue persists, uninstall, reboot, and reinstall the app. Clear app cache/storage before re-adding the account.
- Re-add the account with correct server settings:
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- IMAP:
imap.gmx.com, SSL/TLS on port 993
- IMAP:
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- SMTP:
smtp.gmx.com, SSL/TLS on port 465 or STARTTLS on 587
- SMTP:
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- Auth: Use your full email address and current password; avoid “password only” if your app supports OAuth.
- Disable and recreate app passwords: If you use two-factor authentication, generate a fresh app password, use it once, and revoke it if you switch devices. This resets stale tokens that can cause login loops.
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- Adjust keep-alive/interval settings: In your app, set IMAP IDLE refresh to 3–5 minutes. If the app doesn’t expose this, try a different client that respects modern server timeouts.
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- Check time and certificates: Ensure your device time is set to automatic (NTP). Certificate errors often stem from clock skew. If you still see cert warnings, update your OS root certificates.
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- Test on the GMX mobile app: If the official app works, your third‑party client is likely incompatible with the new auth rules. Migrate or request an update from the developer.
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- Verify device trust: Log into GMX web, go to security settings, and look for unrecognized devices. Approve or remove old entries. This clears device fingerprint conflicts.
Pro tips:
– If you manage multiple accounts, test one at a time to avoid cross-contamination of settings.
– For enterprise networks, whitelist GMX’s IMAP/SMTP hostnames and ensure your firewall isn’t inspecting SNI in a way that breaks TLS handshakes.
– If you’re on a managed device, contact IT; they may need to update MDM policies to allow the new auth flow.
Real-world example:
A user on Android saw “sync stopped” overnight. Webmail worked, but K-9 Mail kept failing. After switching from ISP DNS to 1.1.1.1, flushing DNS caches, and reducing IMAP IDLE to 3 minutes, sync resumed immediately. No password change needed.
Compatibility, Availability, and Pricing (If Known)
Compatibility: Webmail works on all modern browsers. IMAP/SMTP works on clients supporting TLS 1.2 or higher. Older Android versions with outdated system libraries may struggle; upgrading the OS or switching to the official GMX app usually resolves it. iOS 15+ and recent macOS Mail are fine, provided time sync and certificates are current. Windows Mail and Outlook are compatible if updated. Linux clients (Thunderbird, Evolution) work with the correct ports and SSL settings.
Availability: The service is operational overall. The issues reported today are regional and intermittent, tied to DNS routing and client compatibility, not a global outage. If your webmail loads, the platform is available; your client or network path is the blocker.
Pricing: GMX’s core email remains free for personal use. Business tiers exist with SLA and support options. There is no pricing change associated with today’s authentication tightening. If you’re on a free plan, you may be prompted to verify your device more often, but you won’t be charged for fixing connectivity issues.
Unknowns: We don’t have official confirmation on the exact gateway IP changes or the precise timeout windows for IMAP IDLE in every region. If you need those specifics for firewall rules, contact GMX support directly or consult your ISP’s network team.
Common Problems and Fixes
Symptom: Login loop on mobile app; webmail works.
Cause: Stale token or device trust mismatch after an OS update.
Fix: Re-add the account with a fresh app password; approve the device in web security settings.
Symptom: “Cannot verify server identity” on IMAP.
Cause: Certificate validation failing due to clock skew or outdated root certs.
Fix: Enable automatic time sync; update OS; clear app cache and retry.
Symptom: SMTP fails with “connection refused.”
Cause: DNS pointing to old gateway IPs; ISP-level filtering.
Fix: Flush DNS, switch to 1.1.1.1/8.8.8.8, verify port/SSL settings.
Symptom: Inbox not updating; “sync stopped.”
Cause: IMAP IDLE timeout mismatch; aggressive battery optimization killing background sync.
Fix: Reduce refresh interval to 3–5 minutes; disable battery optimization for the mail app; use official app if third-party fails.
Symptom: “Password incorrect” despite correct password.
Cause: Basic auth blocked; app not using OAuth or modern handshake.
Fix: Enable OAuth if available, or create and use an app-specific password; update the app.
Symptom: Intermittent “host unreachable.”
Cause: Regional routing issue or SNI inspection by firewall.
Fix: Change network, bypass corporate proxy temporarily, or ask IT to whitelist mail hosts.
Security, Privacy, and Performance Notes
Security: The new checks are designed to block credential stuffing and session hijacking. When GMX terminates idle connections faster, it reduces the window for session reuse attacks. If you’re asked to re-verify a device, that’s a feature, not a bug. Always review active sessions and revoke anything you don’t recognize.
Privacy: GMX processes authentication metadata to detect anomalies. This includes IP, user agent, and device fingerprint. If you travel or use VPNs, expect more verification prompts. Use a reputable VPN to avoid triggering fraud filters, and avoid public Wi‑Fi for initial re-auth until the device is trusted.
Performance: Shorter keep-alive windows increase battery usage slightly because the app must reconnect more often. If you’re on limited data, set sync to “only on Wi‑Fi” or increase fetch intervals. Disable unnecessary folder subscriptions (e.g., spam/trash) from mobile sync to reduce overhead.
Best practices:
– Keep your OS and mail app updated.
– Use OAuth where available; avoid storing plain passwords.
– Enable two-factor authentication and app passwords for third-party clients.
– Periodically clean old devices from your account.
– Use a trusted DNS resolver and avoid invasive “security” software that inspects TLS.
Final Take
Today’s GMX Störung reports are mostly client-side or network-path issues, not a platform-wide outage. If webmail works, focus on your app, DNS, and device trust. The quickest path to normal is: verify webmail, switch networks, flush DNS, update/reinstall your app, and re-add the account with modern settings. If you need a quick status check, consult GMX Email Status before deep troubleshooting. Most users resolve this in under 10 minutes by modernizing their client or adjusting DNS.
For deeper guidance on related topics, see GMX Störung. If you’re still stuck after following the steps above, collect your exact error message, client version, and network type, then contact GMX support with those details.
FAQs
1) Why does webmail work but my phone won’t sync?
Your account is fine; the app is failing the new handshake. Update the app, flush DNS, reduce IMAP IDLE interval, and re-add the account with the correct ports.
2) Is GMX down right now?
Likely not globally. Check GMX Email Status for regional reports. If webmail loads, the platform is operational; the issue is client or network specific.
3) Do I need to enable two-factor authentication?
Not strictly required, but strongly recommended. If you enable it, use app-specific passwords for third-party clients. This avoids login loops caused by basic auth blocks.
4) Which ports and settings should I use?
IMAP: imap.gmx.com, port 993, SSL/TLS. SMTP: smtp.gmx.com, port 465 (SSL/TLS) or 587 (STARTTLS). Use your full email as the username. Prefer OAuth if your client supports it.
5) How do I fix “cannot verify server identity”?
Check your device time is automatic, update OS root certificates, clear the app cache, and retry. If it persists, try a different network or switch to the official GMX app.