From: The Post Office <postmaster>
Sender:	mailer-daemon
Subject: Usage of IP-number as an address (error)

The following message arrived with illegal envelope data, typically a
mangled address that doesn't obey the RFC822/976 protocol specification.

Some  BSD sendmail  systems allow users to use IP-addresses as address
for delivering mail.   Such kludge format should NEVER be used.
Furthermore proper format for it is not:
	foo@12.34.56.78
but:	foo@[12.34.56.78]

Again: THIS KLUDGE SHOULD NEVER BE USED!

Your message is being returned unprocessed.

The following annotated envelope headers illustrate the error(s):
