RE: MUA, MTA and SPF

> -----Original Message-----
> From: Jesus Duarte [mailto:[email protected]]
> Sent: Friday, January 06, 2012 12:23 PM
> To: [email protected]
> Cc: David Hudson; Torrie Hughes; "Marc Hudson"@b-lb-mx-quonix.listbox.com
> Subject: [spf-discuss] MUA, MTA and SPF
> 
> I would think that SPF would key in on the IP of the MTA and not the MUA.

It uses as one of its inputs the IP address of the SMTP client, which in your case is the MUA itself.

> All of our MTAs are listed in our SPF RR.  My question then, is this an
> error in SPF checks?  If not, is there some sort of "tweak" we are
> missing in Postfix for authenticating our users within our IP address
> space short of adding all of those IPs to our SPF record?  Or do we
> need to contact all of our customers and tell them they must use SMTP
> authentication?

I don't think postfix does SPF natively, but rather via a plugin.  You would thus configure the plugin not to do SPF evaluation against your MUAs, or list in your domain's SPF record all the IP addresses for your MUAs.  (You probably want the former.)

-MSK