Resolve error "Temporary Lookup Failure" when sending Postfix emails

Home > Search

When using telnet to create a test Postifx email, error 451 4.3.0 <>: Tempoary lookup failure appears.

root@example ~ $ telnet 25
Connected to
Escape character is '^]'.
220 localhost ESMTP Postfix (Ubuntu)

helo server
250 localhost

mail from:
250 2.1.0 Ok

rcpt to:
451 4.3.0 : Temporary lookup failure

rcpt to: jeremy@example
451 4.3.0 : Temporary lookup failure

rcpt to: jeremy@localhost
451 4.3.0 : Temporary lookup failure

221 2.0.0 Bye
Connection closed by foreign host.


To identify the cause of this issue, on the Postfix server, use try sending a test email to root@localhost.

rcpt to: root@localhost


If the error appears when using root@localhost, there is likely some issue with the configuration of Postfix in the /etc/postfix/ file. View the mail logs to see if there are events that help to identify the issue with the Postfix configuration.


Add a Comment

We will never share your name or email with anyone. Enter your email if you would like to be notified when we respond to your comment.

Please enter in the box below so that we can be sure you are a human.