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

Jonathan E. Brickman jeb at joshuacorps.org
Thu Mar 12 13:02:07 CDT 2009

It used to be possible to send email direct from any ISP connection via 
SMTP, but as part of the need to stifle spam, this is not usually 
possible anymore. Now we really have to send email through a 
'smarthost', a registered SMTP server of an ISP/WHP, using an 
authentication of some sort. Some smarthosts, e.g., AT&T's, are 
extremely picky: the email "From: " fields have to match either the 
account email address or a list of alternates which can be configured, 
maximum 10. I don't recommend using AT&T's smarthost, though, because I 
have seen its configuration web site fail to work properly too many 
times. I keep a paid vfemail.net account for this purpose (it has a 
special registered smarthost that is very good, and the price is very 
low). If you are keeping a web site somewhere, the WHP may have a 
smarthost available for you to use, or not; mine (truepath.com, 
otherwise very highly recommendable) doesn't.

In addition, some smarthosts (e.g., AT&T) are requiring SSL, and some 
aren't. I did once successfully configure Postfix to transmit to AT&T 
for a LAN. The documentation was not very easy to find, I could probably 
find it again (look for SSL auth to smarthost) -- but this was two years 
ago, and AT&T has gotten worse.

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.


> Hi all,
> I've been dabbling with postfix for a couple days and I've so far managed to 
> set it up to retrieve my mail from my ISP and use procmail to filter the mail 
> into the correct mailboxes.
> My only problem is I can't seem to figure out how to set up SMTP to send to 
> address' other than the local ones. I can send to david at buddy using sendmail, 
> but I can't send to david at att.net. Every time I try to send to an outside 
> address using sendmail, (/usr/sbin/sendmail) the message sits in the Mail 
> Queue. But If I try to send an e-mail using postfix (/usr/sbin/postfix) I get 
> an error: 
> Sending failed:
> Sendmail exited abnormally.
> The message will stay in the 'outbox' folde…emove the message from the 
> 'outbox' folder.
> The following transport was used:
>  postfix sending
> I'm wondering if there's something I missed?
> I attached my main.cf file in case anyone needed a look.
> Blessings,
> David M.
> http://www.dmcentral.net
> ------------------------------------------------------------------------
> _______________________________________________
> ChristianSource FSLUG mailing list
> Christiansource at ofb.biz
> http://cs.uninetsolutions.com

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