Local mail delivery needs write access to /var/mail to create lock files.
Evolution has an sgid helper for that (libexec/camel-lock-helper*) however on freebsd it's group owner is "wheel" while /var/mail has group owner "mail".
Executing `chgrp mail /usr/local/libexec/camel-lock-helper*` fixes that.
A commit references this bug:
Date: Thu Aug 6 11:42:05 UTC 2015
New revision: 393653
Make the camel-lock-helper-1.2 application part of the mail group and set sgid.
This allows evolution do do local mail delivery again.
Submitted by: firstname.lastname@example.org