Postfix is delaying some mails
Our corporate mail server is a Postfix running on a Debian Sarge. Recently, I have noticed that some outgoing mails are delayed some time and I do not know why. Here is a line from mail.log
Nov 8 11:15:24 sirius postfix/smtp: 5C5756000CB9: to=<email@example.com>, relay=mail.valoresbancolombia.com[18.104.22.168], delay=4, status=sent (250 Ok: queued as B49E83DC004)
So for example, this mail is delayed for about 1 hour... this is a big problem !!!
Any help or hint would be appreciated.