I would like to pose this question to this list - it seems that the more knowledgable people reside here. I may later open this up to other lists. I have recently had to write a DEADMAIL program to automatically return bad mail to invalid users. (don't ask). Anyway, I have been noticing a problem in the use of the SENDER fields. There are many lists that are set up as monitored lists whereas the final piece of mail sent out to the list has the From field specifying the originator, the Sender field specifies the list and the ReplyTo field specifies the list. My first comment is that should not the Sender field be the list moderator, or even someone in charge of the list if not moderated so that Mail agents would report problems back to the Sender field if the Mail Agent follows RFC822 specs. In any case, I have sent out messages in which the Sender field was the list and I received the undeliverable notices. Why the Mail Agents are not returning the undeliverable mail to the Sender field according to 822 is yet another problem as well. Nontheless, I follow RFC822 and everyone bitches at me for distributing "undeliverable" mail back to lists. I would appreciate comment on this - as to whether I am correct in all that I have said, and whether or not it would be possible to at least have lists set up correctly for when and if RFC822 is implemented correctly in various Mail Agents. - Michael Gettes, Boston University