What MTA ...

[James Gray]

On 13/03/2007, at 6:40 AM, Mikael Syska wrote:

> Hi,
>
> First off ... I dont want to start a flamewar of any kind  
> here ..... please.
>
> I have used Postfix for about a year and its fairly easy to use,  
> used it with VDA ... and multiple domains ... so I wanted to try a  
> new MTA.
>
> One of the 3 others ...
>
> So my question is ... what works best with MS? since Postfix got  
> some issues with MS ( not that it have any effect, after what I  
> have read ) I still wants to try a new ... maybe I will like  
> Postfix best after I have tried the other, you'll never know....

I've used sendmail, exim and postfix with MS.  My order of preference  
is exactly as listed in the previous sentence, with sendmail first.   
The reasons vary but I'll list a few:

Sendmail (Pro's):
- extremely flexible
- rich plugin (milter) library that can be used along side MS without  
major modification.
- very powerful MTA-level anti-spam features (greet pause, bad  
recipient throttles, RBL's, etc, etc)
- scales extremely well
- easiest to integrate with MS.
- easy to implement individual delivery for multi-recipient messages  
(split mail) allowing full use of MailScanner's per-recipient filtering.

Sendmail (Con's):
- mail routing can be a pain depending on your back-end (eg, LDAP,  
AD, NDS, etc)
- configuration can be daunting to the inexperienced, but there are  
plenty of how-to's etc.
- recipient verification can be cumbersome (see comments on mail  
routing).

Exim (Pro's):
- extremely flexible
- most binary distributions have out-of-the-box MySQL support  
(exim4...if that's important)
- very easy to configure and accomplish routine mail setups
- easy to integrate with MS (requires 2 separate processes)
- very powerful MTA-level anti-spam features...but not as many as  
sendmail in my experience.
- very easy to enable TLS/SSL SMTP.
- mail routing and recipient verification can be easily managed from  
a MySQL back-end.
- scales very well.
- powerful server-side delivery filtering and/or sieve scripts.

Exim (Con's):
- Requires two completely separate daemons and configurations for MS,  
but this is extremely well documented.
- Limited "nataive plugin" support, but pretty much anything can be  
used as a "plugin" through Exim's "routers".
- mail routing and recipient verification can be kludgy if your back- 
end is a little esoteric (Active Directory, I'm looking at you!)
- can be used to split multi-recipient messages, but not as  
intuitively as sendmail.

Postfix (Pro's):
- Very easy to set-up and configure
- good MTA-level anti-spam features (but lacks some of exim and  
sendmail's more advanced features)
- IMHO it has a better security track-record than both sendmail and  
exim[1]
- only requires a single daemon
- later versions have support for some (most?) sendmail milters.
- scales well.

Postfix (Con's):
- the Postfix author and community are very "anti" MS.
- much more difficult to split multi-recipient messages, especially  
on heavily loaded system.
- I don't like the plugin model (everything talks to each other over  
sockets)[2]

Some footnotes:
[1] Previous track-records in security have little relevance to  
actual security now.  However, it seems the sendmail developers drag  
their heels on patches compared to both exim and postfix.  I'm happy  
to be proven wrong on that count, but that's just my perception based  
on over 7 years as a full-time mail admin :)

[2] Using sockets to talk to extensions/plugins can be a benefit in  
very large installations, as you can distribute your plugins across  
physical boxes to spread the load.  However, the model also means  
that some information about the message is not passed to the plugins;  
which is why MS uses the queue files directly (are you reading this  
Wietse?).

There are other Pro's and Con's for all three, but these are the ones  
that jump out at me.  If I knew more about what you are trying to  
achieve, what existing infrastructure you have and how you would like  
to administer the whole system, then I (and others) could provide  
some more specific information.

Take care,

James
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2417 bytes
Desc: not available
Url : http://lists.mailscanner.info/pipermail/mailscanner/attachments/20070315/df0b8bde/smime.bin