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From: Ansgar Wiechers on 11 Feb 2010 01:47
On 2010-02-10 Jeff Lacki wrote:
> On Wed, 10 Feb 2010, Jeff Lacki wrote:
>
>>> in transport:
>>>
>>> myusername(a)myISP.com smtp:[mail.optonline.net]:25
>
>> This means email sent through your Postfix server that is addressed
>> to myusername(a)myISP.com will be relayed to mail.optonline.net. Is
>> that your goal?
>
> Yes sorry for the confusion. I want to send email from basically
> anywhere in the world through my postfix server. Since my email
> address that I use is constant, can I setup postfix to recognize that
> its me (from anywhere - based on my email address) and relay it
> through "mail.optonline.net" as in my example above?
>
> The email address I use is not my servers domain name however, but can
> postfix recognize my From field and allow it to relay? If so, how do
> I do this?

That would make your server an open relay to anyone spoofing your
address as the MAIL FROM address.

Don't do that. Ever.

Regards
Ansgar Wiechers
--
"Abstractions save us time working, but they don't save us time learning."
--Joel Spolsky

From: Ansgar Wiechers on 11 Feb 2010 01:55
On 2010-02-10 Jeff Lacki wrote:
> Thanks, thats good advice for sure. Turns out Im not able to get to
> port 25 on my postfix box from my current location.
>
> Whats odd is that I went to 2 other servers on the net and I can
> telnet to port 25, but here at home, I cannot. I can telnet to port
> 22, 53, but not 25. I checked my iptables on both machines and even
> disabled them (flushed all the rules), no luck.
>
> Anyplace where postfix would deny a specific ip from even connecting?
> I cant imagine where that would be, especially because my IP is
> dynamic here at home.

The reason most likely isn't your Postfix, but the ISP blocking outbound
connections to port 25/tcp. The rationale behind this is to prevent home
computer bots from sending spam.

Use submission (SMTP with authentication enforced on port 587/tcp)
instead. You should use authentication (and encrypted connections)
anyway, if you want to relay through your MTA from anywhere in the
world. See Postfix' TLS README:

http://www.postfix.org/TLS_README.html

Regards
Ansgar Wiechers
--
"Abstractions save us time working, but they don't save us time learning."
--Joel Spolsky

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