Bill Kwok wrote:
Please correct me if I am wrong. What Erik means is that, by default,
all SMTP communication will go through port 25. It includes server to
server and client to server communication. If you setup rblsmtpd (or
similar program) to check the incoming email again spam, all emails
going through port 25 will be checked. It includes the emails
submitted by you and your users.
In order to avoid such problem, you may divide the emails into two
portion:
1. Email from other servers - It will use port 25 and rblsmtpd will
scan the incoming mail as usual.
2. Email from local users - Local users will need to change their
mail client setting, so that it will submit email to the server
by using port 587 (the submission port). There's no rblsmtpd
checking on port 587. But instead, users must authenticate
himself / herself before they can submit email.
Very nice Bill. That lays it out perfectly, AFAIK.
