On upgrading server software

Short story: when upgrading a production system, always check the release notes of the new version.

Long story.

After the first upgrade of the server following the release of the new Debian stable, I was no more able to send e-mail from my home pc, but I am still able to send from the server itself, which is running Debian testing, so in the following days of the Debian release, testing got a lot of upgrade as usual.

This upgrade also boost postfix to the 2.1.0 release.

Sending mail from my home pc, then result in the error:

May 11 09:28:22 localhost postfix/smtpd[17094]: connect from unknown[]
May 11 09:28:24 localhost postfix/smtpd[17094]: NOQUEUE: reject: RCPT from unknown[]: 554 5.7.1
: Relay access denied; from= to= proto=ESMTP helo=
May 11 09:28:24 localhost postfix/smtpd[17094]: lost connection after RCPT from unknown[]
May 11 09:28:24 localhost postfix/smtpd[17094]: disconnect from unknown[]

It turn out that from this release on, to be able to have a relay (from home I send mail using my server and not the provider’s one), you should put the client restriction in the directive


instead of the old


as always in the main.cf file

I discovered this the hard way, since I was in a hurry to send a mail, and before I can find this change, I tried a gazillion other solutions and also checked for every blacklists in the case the server and/or my provider nerwork were blocked.
So, lessons learned:

  1. Always read the release notes (or at least, check them for the important software)

  2. Do not try massive upgrade past 10.00 pm or you will end to lose sleep and do not solve anything anyway, at least until the next morning

  3. If you need to send a very urgent email, send it before trying a massive upgrade :-D