So should I upload this to CPAN? Did my coworker miss something close to this already on CPAN?
There are a lot of modules on CPAN dealing with e-mail addresses. Unfortunately, a lot of them are rubbish. You might want to take a look at the Perl Email Project if you haven't already.
If I understand you correctly (without specifically having worked through the regexen), you consider the following addresses to be equivalent:
"Eve" <firstname.lastname@example.org> (Rybody)
What about addresses with different top-level-domains, but equal second-level-domains? For example emails from/to
are all routed from/to the same mailbox. Are they equivalent to you?
In either case all you need is a tokeniser. It will allow you to compare exactly what it is you need to determine equivalency.
Some of the existing modules tokenise the addresses internally to some extent, but Email::Address also gives you nice accessors for the resulting tokens, so it would be my prime choice for solving what I perceive your problem to be.