On Mon, 10 Apr 2006 16:08:15 EDT, "Gartner, James" said: > The unknown user errors are strange: > SOFTBOUNCE [log in to unmask] 5.0.0 550 5.1.1 <[log in to unmask]>... User unknown > SOFTBOUNCE [log in to unmask] 5.0.0 550 5.1.1 <[log in to unmask]>... User unknown The 5.0.0 is an "unspecified" error, and Listserv is probably erring on the side of caution - if the box at the other end is confused regarding the nature of the error, it may well decide there isn't an error when you retry. ;) > BOUNCE [log in to unmask] 5.1.1 Mailer mail02.COLOHFA.ORG said: "550 > 5.1.1 User unknown" RFC3463 is pretty specific about 5.1.1 however: X.1.1 Bad destination mailbox address The mailbox specified in the address does not exist. For Internet mail names, this means the address portion to the left of the "@" sign is invalid. This code is only useful for permanent failures. (Note that your 2 softbounces contain 5.1.1, but in a *later* field. It's the 5.0.0 that matters....)