Open Relay Checker
Check whether a mail server may be acting as an open relay. Open relays allow anyone to send email through the server, enabling spam and abuse.
Email Domain
What is an Open Relay?
An open relay is an SMTP server that accepts and forwards email from any source to any destination without authentication. Spammers exploit open relays to send bulk email while hiding their identity. Domains with open relays are quickly blacklisted.
DNS Analysis Only
Full open relay testing requires sending SMTP commands (EHLO/MAIL FROM/RCPT TO) directly to port 25, which browsers cannot do. This tool performs DNS-based analysis only. For a complete relay test, use MXToolbox, Mail Tester, or telnet 25 from a command line.