in reply to Regex Expression to filter email for Barracuda Email Appliance

Why has it to be a single regex implementing all the logic?

You could simply match /From: (.*?) <(.*?)>/ and than check $1 and $2 with Perl

Far better maintainable.

Unless ... this isn't really a Perl question?

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In Section Seekers of Perl Wisdom