in reply to email check
You should use the one that uses a module. Namely, RFC::RFC822::Address.
But seriously, why the "no modules" constraint? If you *really* can't use a module, for some bizarre reason, I suggest downloading the module and putting its code in your own source file (take care to heed the copyright notice in the module, though).
"One word of warning: if you meet a bunch of Perl programmers on the bus or something, don't look them in the eye. They've been known to try to convert the young into Perl monks." - Frank Willison