[Mimedefang] blocking | and bad syntax in "from" address

[Joe Arnstein]

Hi all,

I've been noticing a lot of spam coming in with characters in the "from"
address that don't work or are likely to be forged.  These cause a
backup in our outbound queue (lots of NDRs) so I'd rather they be
rejected right off the bat.
 
from=<_mohammad at ameritech.net>
from=<Puri|puri at nt.com>
from=<Rauly|rauly at ns4b.com>
from=<.samuel at whereever.com>
from=<80/joan.smith at spamcorp.com>
from=<A/uykgYBAQAIAOgB9QAAAAAEAAApGQ at edailydiscounts.com>

Do any of the rfc's say this is improper syntax or forbiden characters?
Should I block this?  Can I block it? And if so can someone recommend a
good way to do it?  

Thanks,
Joe Arnstein