Hello,
I have been going through various docs on the net about sasl
authentication in postfix. In the system that I have set up at a
client's place, mails are going fine but there is a small issue that
needs to be corrected. The setup is a group of machines on LAN running
Outlook Express mail clients and a Linux box running postfix pushing all
mails to the main ISP's smtp server. Since It is a relay server, I have
used the parameter relayhost = [smtp_of_ISP]:25 in the main.cf file. The
sasl auth is using smtp_auth_enable and not smtpd_auth_enable and the
user names/passwords are listed in the /etc/postfix/sasl_password file.
The only *smtpd* related entry is smtpd_recipient_restrictions =
check_recipient_access hash:/etc/postfix/recipient_access, reject.
Mails are going as required and only to those in the recipient_access
list as required. Now if an employee has left and his/her entries are
removed from the postfix box as well as the ISP server mail accounts,
the Outlook Express mailer can still send mails as that non-existent
user. What I found through more reading of docs is that my OE accounts
can send mails even without authentication as I don't have
smtpd_auth_enable and the LAN is in my mynetworks parameter. Not a big
problem as it is local and under control and the OE account can be
deleted for that user. However, why is the ISP allowing this unknown
user which postfix is relaying when I have everything set in the
smtp_auth_ part of postfix? Suppose there is a flaw in my settings,
shouldn't the ISP's mail server reject those mails when the username and
password do not match with their list? That user has been deleted from
their server.
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Regards,
Rony.