obscure email address formats

ArkanoiD <[email protected]> Tue, 24 May 2011 00:30:24 +0400
Newsgroups gmane.comp.security.firewalls.wizards
Message-ID <[email protected]>
Is there any good reason to allow email addresses (in smtp, imap and alikes)
in any format different from mailbox@fqdn ?

There is plenty of other stuff defined in RFCs and I wonder if anyone really uses it so
I should *not* just filter it out.