Postfix SMTP-AUTH Issue - Solved! I followed the tutorial called “Virtual Users And Domains With Postfix, Courier And MySQL (Fedora Core 5)”. I did it on Fedora 8. Everything went fine, with one or two minor issues that I solve quickly; except one annoying problem that I have no idea how to solve it. The problem is that only the first account ever created, for each virtual e-mail domain, is capable of using the SMTP-AUTH feature, the next added account keeps asking for password, and the “maillog” shows: Code: -May 9 11:12:28 punk postfix/smtpd: warning: unknown[192.168.111.254]: SASL LOGIN authentication failed “(Obs: The password is correct, I’ve checked that, in IMAP, for example)” -May 9 11:12:28 punk postfix/smtpd: lost connection after AUTH from unknown[192.168.111.254] In "messages" log file: Code: May 9 17:00:31 punk saslauthd: do_auth : auth failure: [user=<username>(without realm)] [service=smtp] [realm=<realmname>] [mech=pam] [reason=PAM auth error] With “My Outgoing server (SMTP) requires authentication” (@ Outlook) turned off, the sending is automatically rejected, as expected. With all the first accounts ever created, per domain, everything works fine (with internal and external delivers). EDIT: Only the first account ever added works. The others, with no visible reason, where using the username/password of that account for smtp-auth, when sending e-mails. They dont work with their credentials. Does Postfix/SMTP-AUTH has some kind of "Max Connections" per IP protection? Thanks in Advance!