Hi,

I am trying to set up a home mailserver in my basement mostly for the learning experience. I am using postfix and am able to receive email, but not send. It seems like my outbound port 25 is blocked by my ISP and I've seen that the workaround is to use mail submission on 587. I set it up using various instructions on the internet but according to the log, my server is still trying to connect to the recipient's server using port 25. Why is that, shouldn't it be connecting using 587? Or is 587 just how the client connects to my mail server which then sends the mail to the recipient on 25 no matter what?

If that is the case, then I could use my ISP's (Rogers) smtp server to relay the mail I guess. I would connect to that using 587, and the ISP's server would connect to the recipient using 25?

Jacob

The way it normally works is that mail submitted on port 587 may be relayed to any other mail server on the internet. Mail received on port 25 is only accepted for local, known recipients. Port 587 requires authentication to prevent abuse by spammers; port 25 does not.

Something that you should also be aware of is that many mail servers now check against known ISP IP ranges and may reject mail sent from a "residential" IP range.