At last, you can get some mail.
Yes the packages are both disabled by that command. Judging by the message you're seeing I'd say it's a problem reading one of the files that's passing through the mail system. Now, that can be caused by not having the compat libs installed and/or problems with convertd but I'm not sure it's the problem in your situation. I'm not great on debugging problems in distros like debian but I'd suggest you post on their forums and see if anyone has come across this problem before or could at least point you in the right direction.
I seem to have read every post I could find on google about this error but the only one that made sense is the one you found about net::server being a problem. As I mentioned that's fixed in later releases of Amavis. I've also seen mention of problems with perl and this error, you could try removing perl then reinstalling it and see if that helps - but I'm really out of ideas with this one. Maybe one of our more experienced debian users can offer some insight.