Mailinglist Archive: opensuse (3901 mails)

[Michael James <Michael.James@xxxxxxxx>]

On Mon, 24 Jan 2005 12:27 pm, Carlos E. R. wrote:

> How on earth do I tell postfix to use diferent relays
> based on destination address, from address,
> and posibly, ISP used to connect each time? 

Best technical solution to the many-ISP situation
 is to have an authenticated SMTP host
 somewhere on the internet and always use it.

So the SMTP host effectively says, "Set up an encrypted channel,
  and prove that you're you,  then I'll let you relay from anywhere."

Gmail provide this (and are pretty reliably available).

Always sending through the same SMTP relay
 becomes necessary to enable SPF records.

SPF are DNS records that specify which SMTP hosts
 are allowed to send mail for your domain. (reverse MX records)
SPF fixes all those virii flooding the internet with yours
 and my email picked out of some outlook address book
 and filled in as the sender.
SPF lets a mailhost say, "Not sent from an authorised host, DROP it".

Have a look at:	http://spf.pobox.com/

-- 
Michael James                         michael.james@xxxxxxxx
System Administrator                    voice:  02 6246 5040
CSIRO Bioinformatics Facility             fax:  02 6246 5166