Free email server checker
Check any IMAP, POP or SMTP server’s encryption, certificate, and the sign-in methods it supports – including whether it still accepts passwords or needs OAuth 2.0.
We never send a username or password – we just connect, start encryption, ask the server what it supports, and disconnect. Don’t know your server name? Use our settings finder.
What do the results mean?
SSL/TLS and STARTTLS are the two ways email connections are encrypted. SSL/TLS (ports 993, 995 and 465) encrypts from the start; STARTTLS (ports 143, 110 and 587) connects without encryption and then upgrades. Your app must be set to the right method for the port, or you’ll see errors like wrong version number.
Sign-in methods are the ways an app can log in. PLAIN, LOGIN and USER/PASS send a password; XOAUTH2 and OAUTHBEARER use an OAuth 2.0 access token instead. Some providers – including Microsoft 365 and Google – still list password methods but reject them.
Server needs OAuth, but your app only supports passwords?
Auth-Email signs in to Microsoft 365, Outlook, Gmail and other OAuth 2.0 providers on your app’s behalf, so any email app, printer, scanner or script can keep using IMAP, POP, and SMTP with a normal password.
Frequently asked questions
What does the email server checker test?
It connects to the IMAP, POP or SMTP server you enter, negotiates encryption (SSL/TLS or STARTTLS), checks the server’s certificate, and lists the sign-in methods the server offers – such as PLAIN, LOGIN or XOAUTH2. It never sends a username or password.
The server lists PLAIN or LOGIN – does that mean password sign-in works?
Not necessarily. Microsoft 365 still advertises password sign-in for SMTP, but rejects it when basic authentication is disabled, and Google lists password methods but only accepts app passwords for personal accounts. If you see XOAUTH2 or OAUTHBEARER, the server supports OAuth 2.0 sign-in.
Which ports can I test?
The standard email ports: 993 and 143 for IMAP, 995 and 110 for POP, 465, 587 and 2525 for sending email (SMTP submission), and 25 for checking a domain’s incoming (MX) mail servers.