[CS-FSLUG] using postfix or sendmail to send mail

Jonathan E. Brickman jeb at joshuacorps.org
Thu Mar 12 13:39:16 CDT 2009

Agreed.  I should have mentioned that commercial-grade broadband accounts with statics often include a very small subnet, even though they don't always advertise it.  But some don't offer a static at all, or even if they do, don't permit reverse DNS, and reverse DNS has to be right for it to work.


-----Original Message-----
From: "Frank Bax" <fbax at sympatico.ca>
Sent: Thursday, March 12, 2009 2:34pm
To: "A Christian virtual Free Software and Linux Users Group." <christiansource at ofb.biz>
Subject: Re: [CS-FSLUG] using postfix or sendmail to send mail

Jonathan E. Brickman wrote:
> Your ISP is almost certainly blocking SMTP traffic from its clients; 
> many do these days. It is possible to build your own smarthost, given a 
> more expensive commercial Internet connection explicitly set up for the 
> purpose, but there are more things to do. You'll need a static IP, 
> forward and reverse DNS on that IP, and an SPF record ( www.openspf.org 
> ) to do well. And within 24 months DNSSEC will start to get serious; 
> that will have very interesting ramifications.

If you decide to go with static ip address; you should have ONLY the 
mailserver at this ip address.  If you put the static ip address on a 
NAT router; then you expose yoursefl to different problems.

I recently had to fix a situation where a company had this setup.

A workstation at this site got infected with a spambot.  The volume of 
spam caused the static ip address to be blacklisted; causing problems 
for outgoing email from the mail server.

If you want a static ip as Jonathon describes; that you should seriously 
consider two (or more) static ip address and put mail server on a 
separate ip than the rest of computers at the same site.

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