According to rfc 822 a message id must
be enclosed in <> and contain an address,
i.e. some simple words separated with
an @.

I haven't tried it, just looked at the source,
 but 

messageid = "%s.%s.%s%s-%s"%(time.time(),
 random.random(),
 classname, nodeid, 
 self.MAIL_DOMAIN)

in mailgw.py and elsewhere breaks this rule.