>> Well, except http://tools.ietf.org/html/rfc6854 >I do not see anything in that doc that makes it valid to have a From >field with no domain name. Section 2.1: from = "From:" (mailbox-list / address-list) CRLF In RFC 5322 sec 3.4: address-list = (address *("," address)) / obs-addr-list address = mailbox / group group = display-name ":" [group-list] ";" [CFWS] So this is valid: From: Redacted for your own good :; That's deliberate; the use case we had in mind is EAI mail downgraded by a POP or IMAP server where there's no way to turn the EAI address into an ASCII address. R's, John