I cannot reproduce your problem with `cpan` alone, but one can get such
"Permission denied" errors, when the path towards an @INC entry cannot
be traversed at some point.
root@edbfe5cd3d75:~# mkdir -p /usr/local/lib/site_perl/Foo && chmod
o-rwx /usr/local/lib/site_perl
root@edbfe5cd3d75:~# echo 1 > /usr/local/lib/site_perl/Foo/Bar.pm
root@edbfe5cd3d75:~# perl -MFoo::Bar -e1
root@edbfe5cd3d75:~# su - amavis -c 'perl -MFoo::Bar -e1'
Can't locate Foo/Bar.pm: /usr/local/lib/site_perl/Foo/Bar.pm:
Permission denied.
BEGIN failed--compilation aborted.
So it does not need to be related to the Amavis namespace.
