/var/lib/otrs/Kernel/cpan-lib contains a bunch of perl modules which are also preferred by otrs. Removing cpan-lib and depending on the packages should fix this. Some of the bundled modules are not packaged yet (like Net-SMTP-TLS-ButMaintained).
obsolete in my opinion as that version is not in portage anymore
(In reply to Stefan G. Weichinger from comment #1) > obsolete in my opinion as that version is not in portage anymore Is it the case with the latest version?
Removed in 934a47e2dfc9eb2ff6a38198622584ef458f028d, following last-rites in bug 664326, bug 692398.