FQDN - Fully Qualified Domain Name

When sending email to BlueTie, the sending mail server must respond to a preliminary ‘handshake’ from the BlueTie servers with a Fully Qualified Domain Name (FQDN.) The FQDN identifies the server & domain name. For example, BlueTie’s sending mail server’s FQDN reads outbound1.bluetie.com.This restriction helps to reduce incoming spam, as most spamming machines do not identify themselves with a FQDN.

• Failure to respond with correct FQDN format will cause a permanent error to occur and a bounceback message will be generated.
• Failure to comply will result in a 504 5.5.2 error: HELO command rejected: need fully-qualified hostname. Connection to host lost.

Resolution: If a sender should receive a bounceback message with this error referenced, the administrator for that server should be contacted and the FQDN should be updated to current RFC standards.