[SC-Help] Re: rDNS checks and third party SMTP agents

[Blammo]

On 02 Feb 2005 Iain entered spamcop.help and left
news:ctq32d$5a0$1 at news.spamcop.net: 

> 3. To ensure rDNS checks worked, would it be necessary for the sending
> SMTP server to have a valid MX record or would the servers IP just
> need to apear in the domain records? The significance of a 'valid MX'
> is that this would be a cross-Government *sending* service and we
> wouldn't want inbound mail going to it should the regular SMTP servers
> not be available at any tme for some unexpected reason
> 

As John said, MX records have nothing to do with outgoing mail, MX just 
defines which IP(s) accepts incoming mail.
The From header does not have to be the same as the SMTP Mail From, just 
make sure the SMTP commands are valid. You also have the To: and Reply-To: 
headers, so you can use these to make the message look presentable, without 
causing SMTP problems.

Take a look at this absolutely horrid wizard
http://spf.pobox.com/wizard.html

It took me two days of reading and testing to make any sense out of that, 
so if anyone unfamiliar with it can get it, my hat's off to ya.
And to confuse you even more...
http://spf.pobox.com/mechanisms.html
and
http://spftools.infinitepenguins.net/create.php

And to make matters worse, you can run tests
http://spftools.infinitepenguins.net/check.php
http://spf.pobox.com/why.html
But don't make a mistake or you're screwed because they cache DNS, making 
it rather useless.

If you figure that all out you'll either learn more about SMTP and SPF, or 
become completely confused, depending on what you knew before.
-- 
| Ric
|