Upgrading squirrelmail got me a interesting error message:
* Fatal error: Your configuration file sets the server type "Apache"
* Fatal error: but the corresponding package does not seem to be installed!
* Fatal error: Please "emerge >=net-www/apache-1.3" or correct your settings.
* Fatal error(s) - aborting
This machine had working apache 2.2 up and running.
emerge -av webapp-config
Seems that older webapp-config got confused about something somewhere.