Postfix and forwarding SMTP requests to ISP's SMTP Server

[WizzleyPete]

Hey all. Just one more question on my way to getting my mail server working. My thing is, I want to offer email addresses to other people in my family on my mail server. That way, they can have their first name @colannino.org. However, I do not want to have users send their mail via my SMTP server, since many ISP's block incoming mail from domains that don't have reverse DNS lookups, etc. Instead, I want it to work like this:

1. User sends email through colannino.org.
2. That incoming mail is then forwarded to mail.myispsdomain.com rather than sent directly to the intended recipient via my Postfix server.

How would I go about this? I've heard that it can be done. Also, I believe that my SMTP sever from my ISP requires authentication, so I'd have to enable Postfix to authenticate itself to my ISPs mail server. Thanks in advance.

James

[devon]

Why not have your family use your server for the POP3/IMAP server and their ISP's mail server for SMTP?

[WizzleyPete]

Because I want to configure webmail via Squirelmail. That way, my family can easily check their mail over a secure connection wherever they may go.
Unless of course I can configure Squirelmail to use the smtp server from my ISP directly. Even so though, I'd like to have this configured, if anything, just to say that I've done it and that I know how.

James

[devon]

I would find out if your ISP requires SMTP-AUTH. If not, you should just be able to use Postfix's "relayhost" directive to tell Postfix to use your ISP's SMTP server when sending email.

[WizzleyPete]

I set it to this:

relayhost = smtp.myispdomain.com

Luckily, they do not require SMTP-AUTH. I was very pleasantly surprised Just for future reference, what would I do if the server I wanted to relay outbound requests to required SMTP-AUTH?

By the way, in the message headers in the test emails I sent, I saw no mention of my ISPs smtp server. It still is relayed through them however, correct? Thanks again everyone

By the way, I want to require SMTP-AUTH on my server so that not just anyone can use my server to send mail. How do I do this?

[gladius]

Hi,

There are a few ways of doing it, if you provide pop3, then you can just make them do pop before smtp, which basically means if they can authenticate against a known pop3 account, then you allow them to do SMTP.
What I personally do, is use CYRUS-Sasl, - you need to add sasl to your USE tags, and re-emerge postfix, then emerge cyrus-sasl.
You can then authenticate against PAM (apparently, I couldn't get this working), agains MySQL database of users, or against sasl's own db, sasldb, I use the last option, and on the whole it works very well.

There is a good page here http://postfix.state-of-mind.de/patrick.koetter/smtpauth/
which pretty much gave me what I needed to know.

you should also check your SMTP box for being an open relay
http://www.abuse.net/relay.html


hope that helps

-AJ