Of late I've received several pieces of mail where the envelope sender's
local part contains one or more [unquoted] spaces (quoted spaces might be
legal -- I don't know -- but unquoted ones certainly are not, and I've never
seen a quoted space in an envelope sender address anyway).
They've all been spam. It's n doubt a cheap trick to falsify the bounce
address.
Has anyone seen, or does anyone know of, legitimate email where the envelope
sender contains a space? Is
* ^^From +[^ ]+ +[^ ].* +(Sun|Mon|Tue|Wed|Thu|Fri|Sat)
or
* ^Return-Path: *<.* .*>
at risk of snagging any false positives?