Empty 5322.From address or 5322.From address containing <>

Hi,

it seems there are a number of appliances out on the Internet which generate (in situations where they cannot deliver the message) a non-delivery notification containing an empty From address:

From:

or a non-empty From address that looks like the envelope From for NDNs:

From: <>

in the header of the notification mail. Please note: the above From is the header From (5322.From), not the envelope From (5321.From). Are the above From: header lines valid according to RFC822/2822/5322?

It seems to me they are not valid, as from RFC5322 I get the impression that a From address at least should contain an "@" and a localpart and a domainname, and even if localpart and domainname would be allowed to be empty, there's still the "@" sign...

/rolf