On man 30 nov 2009 21:54:37 CET, Thomas Harold wrote
In general... no. Unless the other company is willing to give you access to their internal list of valid email accounts.
well there is no point for spamassassin to know if a sender is valid recipient or not, whats counts for spamassassin is, is it spam, yes or no
for mta that accepts catchall spammassassin just have more work to do
While the SMTP RFCs do support the "VRFY" command (which would technically let you check whether the "FROM" address exists), probably 99% of all servers have disabled that command to prevent spammers from abusing it to validate their mailing lists. (See RFC 5321 section 3.5.2 and 7.3.)
and what happend is spammers just send to random email addresses and discover user not found ?, nothing mta can do about this
postfix reject_unverified_sender does a vrfy ?, if remote have vrfy disabled it try even harder to use rcpt to
i am unsure if postfix really does it or not -- xpoint http://www.unicom.com/pw/reply-to-harmful.html
