My ISP blocks some ports to prevent, as they say, spamming and so on... I'm not allowed to use smtp port without paying for a "professional service".

I am currently running an Apache server with php and I would like to use mail functions but I can't. I would like also hosting my own email accounts with Sendmail but...

I know that some services exist on the net to overcome such protection (no-ip for example) but if I'm able to avoid paying again, I would prefer an homemade solution. I have access to a linux server at school with a proper connection: could I setup a sort of relay from my server at to home to it using another port than 25 ?

I don't see a problem. You don't have to use 25 port for SMTP. Just set it up for a different port, like 1025. If you plan to use the server to send mail you will just need to change the port in your mail program.

Note that it may be written in your ISP rules that you may not use smtp service, not port. If that's the case, go and find another ISP. This one is not worth your money.

You can also use the other server and setup a port forwarding, but I think you'd need a double forwarding - first to your machine, port differnet than 25 and then on your machine to port 25. Simply forwarding to your machine will not work, because port 25 is blocked.

Yes, I know I can change sendmail port but I would like to have the communication bidirectional (send and receive mails). That's why I say that I plan to use a computer under linux that I have access at school.

I found some interesting results googling about that topics:

http://www.miek.nl/linux/port26.html

That's the same situation.

It would be great if someone on the forum could explains personally what he (she) has done.