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Re: switching from exim to postfix

On Tuesday, May 01, 2012 11:55:20, Riku Voipio wrote:
> On Tue, May 01, 2012 at 12:48:10AM -0400, Chris Knadle wrote:
> > The quoted 2010 survey [2] showed Exim was the most popular MTA (which I
> > found surprising), deployment of Exim growing just slightly faster than
> > Postfix, and everything else falling in popularity.
> I think it is because other distro's have mostly stopped shipping
> anything that listens on port 25 by default.

By default selecting "standard system" during the Debian Squeeze netinstall 
installs Exim, but it only listens on port 25 on localhost, and not the public 
interface.  [IIRC I believe that was the default in Lenny also.]  I'm pretty 
sure this means that by default the local MTA won't show up on the internet.

> > > So yes, switching to postfix by default  would reduce the workload of
> > > email servers around the globe (no need to burn cpu cycles and thus
> > > co2 to convert emails to quoted-printable).
> > 
> > The statistics quoted showed that Exim was most popular, so wouldn't
> > switching to Postfix by default actually be more CPU costly than the
> > reverse?  :-/  [I'm not saying you're wrong, just that I don't see the
> > logic in the argument.]
> The less there are MTA's out there not announcing 8bitmime, the less
> conversions there will be (eventually). While the exim->exim deliveries
> are not generating conversions (unless the MUA does it), exim is still
> only at 34% of mx, not 34% of the traffic.

Yes that makes sense -- DNS MX records are probably easier to test for.  
Agreed that the % of traffic is not captured in the statistics -- however the 
number of MX records per MTA is more relevant than % of traffic per MTA to the 
arugument you brought up anyway, because that had to do with the number of 
installs and thus the number of boxes needing to switch the installed MTA.  
;-)  [BTW I found it odd that Qmail wasn't in the top 20 in terms of 
deployments vs MX records, and perhaps it is in terms of % of net traffic.]

> > I've likewise often wondered if a low-resource MTA like DMA or ssmtp
> > could be the default MTA for Desktop installs (and I've occasionally
> > tried them), but as has been discussed there seem to be some issues with
> > the idea.  In my case for Desktops I want the local MTA to be able to
> > handle sending local outbound mail to a server via port 587 over TLS
> > with authentication, to retry sending at increasing time intervals,
> > using a "queue runner" but without a daemon listening, and to notify the
> > sender on a permanent failure.  Thusfar I've only been able to find all
> > of that in a full-fledged MTA.
> Indeed, switching to a lightweight mta like dma as default makes probably
> more sense than switching by default postfix. I tried ssmpt and it didn't
> work for me.. Would dma do TLS auth and queque fine?

Yes, it looks like it can.  Manpage [1] example setup [2].

The Readme.Debian document that comes with the dma package also states that 
although a cron job is run by default every 5 minutes, that does *not* mean a 
sending attempt is made every 5 minutes -- dma does an exponential back-off on 
successive sending failures.  It can also notify the sender of sending 
failures [and has a "double bounce" setting in case the sender's address also 

I'm testing it now -- looks promising.  Might be worth further consideration 
for a default MTA.

[1] http://manpages.ubuntu.com/manpages/natty/man8/dma.8.html

[2] http://www.dragonflybsd.org/docs/howtos/HowTo_dma_gmail/

  -- Chris

Chris Knadle
GPG Key: 4096R/0x1E759A726A9FDD74

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