When emerging amavis, courier is correctly identified as the MTA, however the ebuild does not do what is required to get amavis working with courier. Reproducible: Always Steps to Reproduce:
Created attachment 40024 [details, diff] Patch from Amavis website Contrib page
Created attachment 40025 [details] Ebuild that applies the courier patch if courier is detected as the MTA
Created attachment 40026 [details] Automake file needed for patch to compile If you get problems about macros not being found, you may need to add this to the /usr/share/aclocal directory
I've attached a working ebuild, the courier patch, and an automake file I needed to get it to compile. I haven't played much with the setting the username amavis runs under. It seems that it needs to be set to 'mail' to work with courier.
Due to lack of maintainership, and to the fact that amavis has been a dead project for quite some time, it has been removed from Portage. Sorry.