Re: [gentoo-user] Re: [OT] Setting up a fall back ISP SMTP in sendmail

[Alan McKinnon]

On Tuesday 20 April 2010 15:53:01 Harry Putnam wrote:
> I think you all are missing something... sendmail is better documented
> than any of the other pretenders.

One has to understand what the various MTAs out there were built to do, and 
what their "feature list" is:

sendmail comes from ancient days. It was written to be able to route almost 
any kind of mail using almost any kind of addressing scheme to and from almost 
any kind of network. So it is quite happy receiving SMTP mail from the 
internet and routing it to a FidoNet address. To do this, it has to reread 
it's routing table with every message, therefore .cf was designed to be 
machine efficient but still use only ASCII characters. Which led to m4 being 
developed to make it easier, and I've even seen more simple apps that are 
front ends to m4. After a while you start asking "Wow, is this complexity 
actually needed?"

Postfix was designed to remove the sendmail complexity from a sysadmin's life 
while still being somewhat familiar. It's claim to fame is the ability to pump 
enormous amounts of mail down a pipe and keep the routing rules simple. I have 
two Postfix relays, both of them can deal with 3 million mails a day without 
breaking a sweat. Let me put that in perspective, it's about 30 mails a 
second, every second. Postfix is so good at this, I can run them as VMWare 
virtual machine.

exim doesn't fare quite as well as Postfix in the raw throughput department, 
but it is very very good at giving the sysadmin efficient filtering/routing 
rules.

qmail is, how shall I put this? Something that Dan wrote? Dan likes to find 
fault in the detail with almost all software and likes to perform experiments 
to prove himself right. He also likes to do all of this his own way with the 
result that his stuff is a square peg and you have a round hole. Most 
sysadmins I know consider the pain of using qmail to not offset the benefit of 
using qmail, therefore they don't use it.

> Now understand, that I am easily the dullest knife in the drawer on
> this list even though by unix/linux standards I'm fairly long in the
> tooth having started my computing skills in 1996 and broke in on
> redhat at that time (using sendmail).  I'm sad to say, I'm still a
> noob in a vast number of areas.
>
> I've used sendmail all that time.  If I can figure out how to use
> it.... It really must not be that hard.  At least not hard to find
> piles of help on google.

Postfix's web site has an enormous amount of documentation on everything 
related to Postfix.

> Admittedly though my usage has always been just a homeboy home lan
> administrator so closest I ever come to using sendmail anything like
> what its target usage base is, would be a home lan mailhub.
>
> Unless, I'm terribly misinformed, sendmail is still the most commonly
> used mta in the unix world of servers.

Yes, you are misinformed. My logs show very little mail being received from 
sendmail MTAs. There may well be large numbers of ancient sendmail installs 
out there, but they do not account for a large fraction of the mail being 
sent. That trophy belongs to Windows zombie bots....

> At least according to http://en.wikipedia.org/wiki/Sendmail
>
> Qmail home page says it is the second most common MTA but doesn't say
> who is first.... its sendmail... I'm pretty sure.
>
> About all the snipes concerning hacking sendmail.cf... I'm sure you
> are all aware that any hacking needs to happen in sendmail.mc... then
> let m4 sort out sendmail.cf.

Even a cursory glance at sendmail shows that it was designed in a time with a 
different mindset and different needs to what we do these days. Sendmail will 
never escape this legacy because it is what it is and that is it's purpose.

It's not as bad as buggy whips, but the same principle is at work.

-- 
alan dot mckinnon at gmail dot com