We are currently having problems with our zimbra email server where-by all of a sudden cannot send emails out coming back with an error rejected address email@example.com. Can get emails in no bother! I have telnet into our mail server port 25 and performed a helo. This is the output
220 mail.coqueths.internal ESMTP Postfix
501 Syntax: HELO hostname
if you read the log file, it might say why the mail was rejected
Jan 29 09:23:34 mail postfix/smtpd: connect from mail.coqueths.org[126.96.36.199]
Jan 29 09:23:34 mail postfix/smtpd: NOQUEUE: reject: RCPT from mail.coqueths.org[188.8.131.52]: 554 5.7.1 <USER@googlemail.com>: Relay access denied; from=<firstname.lastname@example.org> to=<USER@googlemail.com> proto=ESMTP helo=<mail.coqueths.internal>
Jan 29 09:23:34 mail postfix/smtpd: disconnect from mail.coqueths.org[184.108.40.206]
Have you made it onto a blocklist ?
Does internal mail work ?
If you are relaying through another server is it rejecting your mails.
Is mail still coming in ?
tail -f "your log file" as you are sending a message.