Mailbox provider · GMX (Germany)
How to verify a gmx.de email address
Can you verify @gmx.de addresses?
PartlyPartly. @gmx.de often refuses checking servers before the mailbox question.
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The checker does probe @gmx.de, but its server screens or defers unfamiliar checking connections. A refusal at that stage is about the connection, not the address, so it comes back risky ("Server refused our check" or "Mailbox check unavailable") and never invalid. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
Server refused our checkMailbox check unavailableGMX (Germany) addresses usually come back inconclusive from a mailbox check. On 13 October 2026 the gmx.de mail server mx00.emig.gmx.net refused our checking server at the greeting stage, citing the connecting server's reverse DNS (PTR) record. A refusal like that says nothing about whether the address exists.
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Live DNS snapshot: gmx.de
Checked 6 November 2026, 11:12 UTCRead from DNS at the time shown and refreshed at most once a day. MX says where mail for gmx.de goes; SPF and DMARC describe mail sent from it, not whether any one address exists.
- 10
mx00.emig.gmx.netGMX / Web.de - 10
mx01.emig.gmx.netGMX / Web.de
First MX host belongs to GMX / Web.de.
v=spf1 redirect=_spf.gmx.netp=quarantine: meets the requirement and enforces it.
v=DMARC1; p=quarantine; rua=mailto:[email protected]Look up any other domain with the MX lookup or the email provider lookup.
GMX (Germany) at a glance
| Operated by | 1&1 Mail & Media GmbH, Karlsruhe branch (head office Montabaur), GermanySource: GMX imprint (German) |
|---|---|
| MX hosts | mx00.emig.gmx.net, mx01.emig.gmx.netObserved 13 October 2026 (dig MX) |
| Answer to a made-up address | Connection refused at the greeting: 554 gmx.net Nemesis ESMTP Service not available. No SMTP service. Bad DNS PTR resource record.Observed 13 October 2026 (SMTP probe of a made-up recipient, no message sent) |
| Inactive accounts | Free GMX mailboxes may have stored messages deleted after six months with no login by browser, app or mail programSource: GMX terms, section 5.3 (German) |
| Inactive accounts | After one year of inactivity GMX may release the registered address and give it to other usersSource: GMX terms, section 5.3 (German) |
| Postmaster rules | A valid DKIM signature aligned with the From domain is mandatory; a generic reverse DNS entry usually leads to rejectionSource: GMX postmaster requirements (German) |
What GMX (Germany)'s server says about a missing mailbox
GMX (Germany)'s server replied 554 gmx.net Nemesis ESMTP Service not available. No SMTP service. Bad DNS PTR resource record.. That refusal happened at the greeting stage, before the checking server could name any recipient, so it is a verdict on the connecting server, not on the address. SimpleVerifier returns these as risky with "Mailbox check unavailable" and never as invalid, because treating a refusal as "mailbox not found" would delete real customers from your list.
Servers screen connections this way to keep spam out: missing reverse DNS, a low sending reputation or a blocklist listing are the usual triggers. The same screen applies to every checking service that connects from a shared or new IP, which is why gmx.de results differ between verifiers. SMTP verification false positives explains how much to trust each answer.
GMX belongs to the same company as WEB.DE and mail.com, and all three sent the same "Bad DNS PTR resource record" refusal. See also gmx.com.
GMX addresses can be reissued after a year of inactivity
Section 5.3 of the GMX terms lets GMX delete stored messages of a free mailbox after six months without a login. After one year of inactivity it may release the address to other users. An old @gmx.de address may now belong to a stranger who never agreed to hear from you.
GMX's postmaster page makes an aligned DKIM signature mandatory and says generic reverse DNS entries usually lead to rejection. Re-confirm consent for contacts older than a year and check your own sending setup first.
Cleaning gmx.de addresses you can't check
Treat inconclusive gmx.de results as unknown, not bad. The checks that don't need the mailbox still work: format, typo domains, duplicates and whether the domain can receive mail. The free list health check runs those in the browser.
For the rest, use the address's history. An address that signed up, bought or replied recently is very likely live. For old or bought data at gmx.de, send a small batch first and suppress anything that hard-bounces. If the gmx.de share of your list is small, it's often simpler to keep those rows out of a high-risk campaign than to guess.
Common questions
- Can you verify @gmx.de addresses?
- Partly. @gmx.de often refuses checking servers before the mailbox question. The checker does probe @gmx.de, but its server screens or defers unfamiliar checking connections. A refusal at that stage is about the connection, not the address, so it comes back risky ("Server refused our check" or "Mailbox check unavailable") and never invalid. It always checks the syntax, the domain's MX records, disposable domains and role addresses such as info@ first.
- Can I check if a gmx.de address exists without emailing it?
- Usually not from a checking service. On 13 October 2026 GMX (Germany)'s server refused our checking connection at the greeting stage, before any mailbox question, so the result is inconclusive rather than valid or invalid.
- What mail servers does gmx.de use?
- On 13 October 2026, gmx.de published these MX hosts: mx00.emig.gmx.net, mx01.emig.gmx.net. You can look them up yourself with the free MX lookup tool.
- Should I delete gmx.de addresses that come back risky?
- No. For gmx.de, risky reflects how the server treats checks, not the address. Remove the ones that fail format, typo-domain and duplicate checks, then send to the rest in a small batch and suppress whatever hard-bounces.
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