🚀 go-pugleaf

As postmaster, I often receive messages from a A Large Computer
Manufacturer's mail daemon about problems delivering mail to a
site on the other side of their machine. These messages all have
2 or more distinct To: lines in the message headers, much like:

<misc headers>
 .
 .
 .
To: <bounces@large-computer-manufacturer.com>
To: <postmaster@ricevm1.rice.edu>

<rest of message>

In reading RFC 822 and 1123, I can't tell whether this is legal
or not. Before I go after this site's postmaster to Fix This, I'd
like to get the opinion of other people in my situation.

1) Is this behavior legal?

2) I know it's been customary since the Twenex days to put
   multiple addresses on the To: line, but is it mandated
   anywhere other than a desire to prevent your postmaster from
   being crisped by others who have to deal with the error mail?


Thanks in advance.
-- 
David Boyes       |The three most dangerous things in the world:
dboyes@rice.edu   |  1) a programmer with a soldering iron,
                  |  2) a hardware type with a program patch, and
"Delays, delays!" |  3) a user with an idea.