Upgrade question for "Virtual Users And Domains With Postfix, Courier And MySQL"

I have followed Falko's guide in Howtoforge to create a good-working Postfix box. Unfortunately, it has not been upgraded since and I see amavis and spamassassin has released newer versions, along with other packages in the system.

The question is, I'm not sure if an upgrade would work out-of-the-box. I fear it would break some configuration and I would have to re-check it from the beginning. (It was 7-8 months ago and I don't want to go over configuration files after each upgrade).

To make certain, would letting debian upgrade itself with the command "apt-get upgrade" directly, hinder anything useless? I have already held back the kernel, mysql (client and server), postfix, postfix-mysql and postfix-tls packages from upgrades.

Or at least, could I upgrade spamassassin and amavis (and related packages) without problems?

The server is getting a lot of mails and in a remote office, so I don't want to risk it...

Any comments?

NOTE: The related packages installed on the server are:

 

You cannot update Postfix because you will lose the quota feature then: http://www.howtoforge.com/forums/showthread.php?t=4863&highlight=apt-pinning

 

Upgrade...

Actually, I'm not really into upgrading Postfix. What I really want to replace is Amavis-new and SpamAssassin (with Razor and etc.)

The remaining question is, would even that break something up?

NOTE: I have already postponed upgrades for Postfix, Mysql and some other stuff, like the kernel itself, as I said in the beginning.

 

Normally that should be no problem, but you can never know. Make backups before you try it.