How to Check International Emails and Convert Them to Punycode
To check an international email address, convert the domain to its ASCII (punycode) form and see whether the part before the @ is non-ASCII. The international email checker does this for a pasted list. It shows each domain's xn-- form, flags names that need SMTPUTF8, and warns about domains that mix alphabets, all in your browser.
Converting a domain does not show the mailbox exists.
Why international addresses need a second look
The domain half is handled by Internationalised Domain Names: the visible name becomes an ASCII form starting with xn--, and DNS only sees that form (RFC 3492). A non-ASCII name before the @ needs SMTPUTF8 on each server along the route (RFC 6531), and many systems still reject or mangle such addresses.
The by-hand way
- Take the domain after the @ in the address.
- Convert it with a punycode converter, such as the punycode converter.
- Look at the name before the @ for accents or non-Latin letters.
- Test an address with your sending platform before a full import.
The post on internationalized email addresses goes deeper on how the pieces fit.
Step 1: paste the addresses
Paste the addresses, one per line, and press Check the addresses.
Step 2: read the results
Read the ASCII form of each domain, and which addresses have a non-ASCII name before the @.
Step 3: download
Download the CSV with the ASCII domain and address for your sending system.
For domains that look like a real brand but use another alphabet, see the lookalike domain checker.
What this check cannot do
- Conversion uses the browser's own IDNA handling, so unusual characters may be rejected as invalid.
- Whether a given provider accepts a non-ASCII name before the @ is not tested.
- Mixed-alphabet detection is a warning, not proof of abuse. Some real names mix scripts.
- It does not show whether a mailbox exists.
For the background, read internationalized email addresses.
Then check the mailboxes
Converting the domain solves how it is written. Whether the mailbox exists is a separate question. Paste the list into the verify page; the first 100 email checks are free with a Google sign-in and need no card. Every row returns valid, risky or invalid with a reason, and nobody on the list is emailed. Bigger lists are covered by bulk email verification and pricing.
Try it now
Paste your addresses into the international email checker.
Common questions
How do I convert an international email domain to punycode?
The domain is converted to an ASCII form starting with xn--, as defined in RFC 3492. For example, münchen.de becomes xn--mnchen-3ya.de. A converter does it for a whole list.
What is SMTPUTF8?
An extension (RFC 6531) that lets mail servers handle non-ASCII characters before the @. Every server on the route needs it.
Why do some platforms reject accented addresses?
Many systems store only the ASCII form or treat non-ASCII as invalid. Converting the domain before import avoids that for the domain half.
What does it mean when an address mixes alphabets?
A Latin word with a Cyrillic letter that looks identical is a known look-alike trick. It is a warning, not proof of abuse.
Does conversion show the mailbox exists?
No. It only changes how the domain is written.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.