Mailbox provider · GMX Mail
How to verify a GMX email address
Can you verify a GMX address?
Partly. The syntax, mail server, disposable and role checks work, but GMX's server refused our checking connection before the mailbox question in our 23 October 2026 test. Those results come back risky, never invalid, because a refusal says nothing about whether the address exists. Mail history is the only proof either way.
Tuned for gmx.com, gmx.net, gmx.de, gmx.at, gmx.ch. Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Paste your @gmx.com addresses (a mixed list is fine) and check them together.
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GMX verification facts
| Primary mail server (MX) | mx01.gmx.net (run by United Internet) |
|---|---|
| Made-up address, 23 October 2026 | risky in both rounds, about 10.5 hours apart ("Server refused our check") |
| Mailbox probe | Attempted, but the server refused our checking connection before the mailbox question. |
| Catch-all behaviour | Unknown: the server refused before we could ask. |
| Typical results | Risky ("Server refused our check") for well-formed addresses, never invalid from a refusal. Invalid only for bad syntax. |
| Always checked | Syntax, the domain's mail servers (MX), disposable domains, role inboxes (info@, sales@) and likely typos. |
| A list of addresses | Paste or drop it above: the first 100 checks are free with a Google sign-in, no card, results as a CSV. |
| Single-address tool | GMX checker |
From our checker's code and our own dated measurements. Anything we cannot confirm is reported as risky, never valid. Last updated .
How do I check if a @gmx.com address exists? Paste the address into a checker for the syntax, mail server, disposable and role checks; the mailbox step often fails at GMX Mail, because its server refused our checking connection before the mailbox question on 23 October 2026. Those results come back risky ("Server refused our check"), never invalid, because a refusal says nothing about the address.
Can you verify @gmx.com addresses?
PartlyPartly. @gmx.com often refuses checking servers before the mailbox question.
The checker does probe @gmx.com, 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 unavailableWhat we can and cannot confirm at @gmx.com
We can confirm
- The address is written correctly (syntax), and the domain publishes working mail servers (MX).
- Whether it is a disposable or role address (info@, sales@) or a likely typo of a bigger domain.
We cannot confirm
- Usually, whether a @gmx.com mailbox exists: GMX Mail refused our check before the mailbox question, so results come back risky ("Server refused our check"), never invalid.
- Why one verifier gets an answer and another doesn't. The refusal judges the checking server, not the address.
- Whether a person reads the inbox, wants your email or agreed to receive it. No checker can see that.
Anything we cannot confirm comes back risky, never valid.
What we measured at gmx.com
Measured by SimpleVerifier on 23 October 2026 through our production checker and public DNS. No message was sent and no real person's address was used.
| Made-up address, checked twice ~10.5 hours apart | risky both times ("Server refused our check") |
|---|---|
| Primary mail server (MX) | mx01.gmx.net |
| Mail host | United Internet |
| DMARC policy | p=quarantine |
| SPF | published, ends redirect |
| MTA-STS | published |
| DNSSEC | signed (DS record) |
Sources: How 51 mailbox providers answer verification checks, SPF, DMARC, MTA-STS and DNSSEC at 51 mailbox providers, both with CSVs (CC BY 4.0). All datasets: research.
Where your @gmx.com addresses live
Already paying another verifier?
GMX addresses are hard to check reliably. On 7 October 2026 our live checker could not get an answer about a made-up gmx.com address, and GMX refuses connections from servers without valid reverse DNS in its SMTP greeting. GMX's terms also let it give inactive addresses to new customers after a year, so an old GMX address may belong to someone else.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. See pricing
Live DNS snapshot: gmx.com
Checked 6 November 2026, 07:36 UTCRead from DNS at the time shown and refreshed at most once a day. MX says where mail for gmx.com goes; SPF and DMARC describe mail sent from it, not whether any one address exists.
- 10
mx01.gmx.netGMX / Web.de - 10
mx00.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 Mail at a glance
| Operated by | 1&1 Mail & Media, under GMX's general termsSource: GMX terms and conditions |
|---|---|
| Same mailbox system | gmx.com, gmx.us, gmx.co.uk and gmx.fr use mx00/mx01.gmx.net; gmx.net, gmx.de, gmx.at and gmx.ch use mx00/mx01.emig.gmx.netObserved 7 October 2026 (dig MX) |
| MX hosts | mx00.gmx.net and mx01.gmx.netObserved 7 October 2026 (dig MX) |
| Answer to a made-up address | No answer about the mailbox: the check came back unavailableObserved 7 October 2026 (SimpleVerifier's live checker on a made-up recipient, no message sent) |
| Address rule | Up to 10 email addresses (aliases) on one account, across GMX's domains such as gmx.us, gmx.co.uk and gmx.caSource: GMX support: alias addresses |
| Inactive accounts | Messages may be deleted after 6 months with no login; after 1 year GMX may release the addresses and make them available to other customersSource: GMX terms and conditions |
GMX checks the connecting server first
GMX screens connecting servers before it discusses a recipient: a server without a valid reverse DNS (PTR) record is refused in the greeting with a 554, before any sender or recipient is mentioned. On 7 October 2026 our live checker also came back without an answer about a made-up gmx.com address, so treat GMX results as inconclusive rather than invalid.
That reply belongs to the checking server, and a verifier must not translate it into "invalid". The fix is on the sending side: an IP with a PTR record whose name resolves back to the same IP. Reverse DNS for email explains the setup, and the blacklist checker shows whether your IP has other reputation problems a provider like GMX may act on.
Two sets of servers, one brand
GMX's domains split across two sets of mail servers. On 7 October 2026 gmx.com, gmx.us, gmx.co.uk and gmx.fr resolved to mx00 and mx01.gmx.net, while gmx.net, gmx.de, gmx.at and gmx.ch resolved to mx00 and mx01.emig.gmx.net.
A single GMX account can hold up to 10 addresses across GMX's domains, so one person may sign up as [email protected] and [email protected]. We found no GMX documentation on plus addressing, so do not strip plus tags from GMX addresses when de-duplicating.
Inactive GMX addresses can be reissued
GMX's terms allow it to delete the messages in an account after 6 months without a login, and after a year of inactivity to "release the customer's GMX email addresses ... and make them available to other customers." That is address recycling written into the contract.
For list cleaning, the consequence is that a GMX address that verifies today might belong to a different person from the one who subscribed years ago. Old GMX contacts should be re-confirmed, not just re-verified, and repeated bounces treated as final. Recycled addresses are also one of the routes by which spam traps get onto lists.
Common questions
- How do I check if a @gmx.com address exists?
- Paste the address into a checker for the syntax, mail server, disposable and role checks; the mailbox step often fails at GMX Mail, because its server refused our checking connection before the mailbox question on 23 October 2026. Those results come back risky ("Server refused our check"), never invalid, because a refusal says nothing about the address.
- Can I check a list of GMX addresses for free?
- Yes. Paste the list or drop a CSV on this page and sign in with Google: the first 100 addresses are checked free, no card, once per account, and the results download as a CSV. Single addresses can be checked on this page without an account, five a minute.
- Does checking a GMX address send them an email?
- No. The checker opens a connection to the mail server, asks about the mailbox at the RCPT TO step and disconnects before any message is sent. The owner of the address is not notified.
- Why does my GMX address come back risky?
- Because GMX does not let any checker confirm a single @gmx.com mailbox, so the honest result is risky ("Server refused our check"). Risky means unconfirmed, not bad. Send to those addresses in a small first batch, or only where the address came from a sign-up you trust.
- Why can't my verifier check GMX addresses?
- GMX refuses connections from servers without a valid reverse DNS (PTR) record before the SMTP conversation starts, and on 7 October 2026 our live checker could not get an answer about a made-up gmx.com address. Treat GMX results as inconclusive rather than invalid.
- Are gmx.com and gmx.net the same service?
- They are the same brand on two server groups. gmx.com uses mx00 and mx01.gmx.net, while gmx.net and gmx.de use mx00 and mx01.emig.gmx.net.
- Does GMX delete or recycle inactive accounts?
- GMX's terms say it may delete stored messages after 6 months with no login, and after 1 year of inactivity may release the account's email addresses and make them available to other customers.
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