Net-SMTP-SSL is now redundant as SSL support is implemented in Net-SMTP.
This removal should ideally be handled by upstream.
But upstream haven't seen activity since 2012, and the links on thier site still talk about search.cpan.org still being a thing, ... and GBrowse is no longer discoverable on CPAN.
So I guess one option is to retire this package entirely.
Nothing appears to depend on it, maybe its time to put this out to pasture?
I agree that Gbrowse is not actively maintained:
From: Scott Cain <email@example.com>
Date: Tue, 11 Sep 2018 13:23:44 -0700
Gmod-gbrowse mailing list
So, the easiest is really to drop it from Gentoo. @weaver and me spent so much time in this ebuild (and several approaches) but Andrey is retired and I am not interested in studying the perl stuff.