Mailing List Archive: exim: users

exim expert needed

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sailingevi at gmail

Oct 20, 2009, 1:00 PM

Post #1 of 4 (548 views)
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exim expert needed

hi exim-users --

i am revising the email chapter of the unix/linux system administration
handbook and
trying to do an honest job covering the exim MTA, but i don't have much
experience
with exim. i need an exim expert willing to read the generic sections of
the email
chapter and the exim specific sections and make sure that my coverage is:
1) accurate,
2) complete enough,
3) good advice and helpful.

the whole chapter is about 100 pages, 20 of intro generic stuff, 40 of
sendmail (cant
seem to cut it down further), 10 of exim, 20 of postfix, and 10 or so of
amavisd-new.

thanks.

-evi
evi nemeth
co-author: unix system administration handbook
linux adminstration handbook
--
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## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

wbh at conducive

Oct 20, 2009, 1:47 PM

Post #2 of 4 (509 views)
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Re: exim expert needed [In reply to]

evi nemeth wrote:
> hi exim-users --
>
> i am revising the email chapter of the unix/linux system administration
> handbook and
> trying to do an honest job covering the exim MTA, but i don't have much
> experience
> with exim. i need an exim expert willing to read the generic sections of
> the email
> chapter and the exim specific sections and make sure that my coverage is:
> 1) accurate,
> 2) complete enough,
> 3) good advice and helpful.
>
> the whole chapter is about 100 pages, 20 of intro generic stuff, 40 of
> sendmail (cant
> seem to cut it down further), 10 of exim, 20 of postfix, and 10 or so of
> amavisd-new.
>
> thanks.
>
> -evi
> evi nemeth
> co-author: unix system administration handbook
> linux adminstration handbook

Well....

...as one of my ~/exim/configure files alone runs to 39 A4 pages....

Best you are going to be able to do in a 10-page count is to point folks to the
specific documentation on each of those critters, and explain why it really,
really needs to be read and understood. Exim has the best docs and debug
facility going, but there is a steep learning curve to make the best use of it.

Likewise the searchable mailing-list archives. Not to mention at least a list of
the (many) applicable RFC's. And a note to read the entire RFC, not just the
perts one likes..

;-)

All of that should fit the space you indicate, and would be helpful, as so few
newcomers (or old hands..) seem to bother reading any of the available material.

Especially helpful w/r Exim if you could highlight the different place to look
if using the Debian (and Ubuntu) 'exim4' split-configuration variation vs the
everyone-else standard monolithic ~/configure.

Side-issue, but not sure I'd give amavisd-new much of that scarce space if not
covering sendmail (still very, very widely deployed), not to mention ClamAV and
SpamAssassin, which I *suspect* are also more widely used than amavisd.

Then there are maildrop / procmail, various milters and filters .... how to do
smart relaying, configure to meet various MTA needs and deeds, MS Exchange and
other nasties one has to work to, zombie-blocking, blacklisting, DKIM ... more
spam filtering...

....one could easily do a thousand pages on administering mail tools alone.

JM2CW - it's your book...

Bill Hacker

--
## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

wbh at conducive

Oct 20, 2009, 3:19 PM

Post #3 of 4 (502 views)
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Re: exim expert needed [In reply to]

evi nemeth wrote:
*snip*

>
> i am having trouble wrapping my head around the exim config language and
> recognizing what is a language keyword or option name and what is a
> configured variable name. havent yet found a good explanation of the config
> language in the docs.
>

A prerequisite is understanding the smtp 'phases', next that the 'acl's' operate
during a single session, more or less in 'real time', and end with rejecting
ELSE handing-off a message to the queue, with or without added headers and
values in 'acl_m' variables.

The routers and transports are then operated off the queue contents, anywhere
from 'immediately after' to 'q' time later - hence the differences in 'language'
and what things they can and cannot see and do.

As to the acl 'language':

Exim was not written in Forth - but it could have been.

An acl and its logical flow is a vanilla 'case of' Forth word, and dead-easy for
a Forth coder to grok.

But it takes nearly an hour to learn enough Forth from a cold start to grok a
case structure, so I'll not push that route.

;-)

Among the best ways to learn?

- First: Use the debug toolset. No need to actually move any mail, as it can
tell you in selectably gruesome detail all the thing it WOULD do under a given
configuration when fed a sample message - and that includes hand-off to, for
example ClamAV or SA.

- Next: Enable 'ip_literals', set up two instances of Exim, both with
'log_selector = +all', either on two boxes on a crossover-cable or inside a LAN,
ELSE two Exim instances on ONE box, using different ~/configure files, and with
each bound to a different aliased-up IP on one NIC. No cable needed if on one
box - we'll just bounce in and out of the stack.

Put the IP's into /etc/hosts, and simulated 'live' traffic can go in and out of
the stack or over a roll-cable or local switch without ever having to disturb
the outside world, and with no risk of zombot penetration - which you can also
simulate.

When finally ready to go 'live' the smart admin sits on an ssh terminal with
something like:

tail -f -n 200 /var/log/exim/mainlog

And not just for an hour...

;-)

When satisfied that all is well, don't forget to back-down the 'log_selector =
+all' to something less hungry for disk space. And do come back and spot-check
frequently, even on a server that has been up for 2 or more years w/o reboot.

Any service as potentially easily abused as an MTA should be subject to plenty
of configuration testing before being opened-up to the world at large, and given
frequent monitoring thereafter.

Running an MTA is not to be done carelessly. Think of it as a public restaurant.

Quite welcome when kept clean and serving wholesome food.

But if you allow it to become dirty and spread disease, the mentors of those
who've been poisoned will hunt you down and lynch you in a New York minute...

;-)

Bill

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## List details at http://lists.exim.org/mailman/listinfo/exim-users
## Exim details at http://www.exim.org/
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addw at phcomp

Oct 21, 2009, 1:59 AM

Post #4 of 4 (506 views)
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Re: exim expert needed [In reply to]

On Tue, Oct 20, 2009 at 02:00:20PM -0600, evi nemeth wrote:
> hi exim-users --
>
> i am revising the email chapter of the unix/linux system administration
> handbook and
> trying to do an honest job covering the exim MTA, but i don't have much
> experience
> with exim. i need an exim expert willing to read the generic sections of
> the email
> chapter and the exim specific sections and make sure that my coverage is:
> 1) accurate,
> 2) complete enough,
> 3) good advice and helpful.
>
> the whole chapter is about 100 pages, 20 of intro generic stuff, 40 of
> sendmail (cant
> seem to cut it down further), 10 of exim, 20 of postfix, and 10 or so of
> amavisd-new.

Post the chapter here, or put up a URL where we can read it.

--
Alain Williams
Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer.
+44 (0) 787 668 0256 http://www.phcomp.co.uk/
Parliament Hill Computers Ltd. Registration Information: http://www.phcomp.co.uk/contact.php
Past chairman of UKUUG: http://www.ukuug.org/
#include <std_disclaimer.h>

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## Exim details at http://www.exim.org/
## Please use the Wiki with this list - http://wiki.exim.org/

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