Re: Sendmail vs. ?

[Craig Sanders <cas@taz.net.au>]

On Wed, Jun 27, 2001 at 08:48:19AM -0700, Duane Powers wrote:
> security conscious
> virtual email accounts, likely using LDAP
> spam control
> ease of configuration
> 
> I"m kinda leaning toward postfix, but that's just because I like the 
> cover of the book I saw at borders yesterday <g>

postfix is very good at all four of your criteria.

it's also very easy to migrate to postfix from sendmail - it's designed to
be mostly backwards compatible - e.g. you can use the same aliases,
transports, virtuser etc files.

the formats of those files are either the same, or backwards compatible
- e.g. postfix's virtual table allows multiple addresses on the RHS of
the table so you can have a message delivered to two or more mailboxes.
with sendmail if you wanted to do that, you had to create an alias with
two or more addresses and then make the virtuser table entry point to
the alias.

a useful feature of postfix while you're converting a system from
sendmail is the "softbounce = yes" feature. that causes all mail that
would bounce to just be rejected with a "4xx try again later" code.




the following advice applies if you're running a mail server for dozens
or more people. if it's just a home mail server handling your own
personal mail you may prefer to do it the quick and dirty way and risk
bouncing a few messages...

whatever MTA you go to, the best thing to do is research and experiment
first. get another box (an old pentium or 486 will do), install your new
MTA on it and get a feel for how it works. then trash it and install
sendmail on the same box and configure it in a similar manner to your
main server. test that it works. then convert it to your new MTA and
test that it works. if all goes well, you'll have had a successful
conversion as practice.

now write out a TODO list of each step you have to do in the conversion.
e.g.

 - install postfix
 - shutdown postfix so that it's not accepting mail while i'm configuring it
 - configure /etc/postfix/main.cf
    - [ list of specific features you need enabled/disabled ] 
	- softbounce = yes
 - copy /etc/mail/aliases to /etc/aliases.  run newaliases
 - copy /etc/mail/transport to /etc/postfix/transport.  edit if required.
   run postmap transport
 - copy /etc/mail/virtuser to /etc/postfix/virtual.  edit as required.
   run postmap virtual

...etc.

if you plan out exactly what you are going to do then there is very
little chance of anything going wrong.

finally, begin the migration of your real mail server. tick off each
step as you do it. take it slow, and don't panic. the slow methodical
approach is the best way here.

monitor the log files when you're done, and shutdown the MTA (e.g. run
/etc/init.d/postfix stop) at the first sign of trouble so that you can
investigate and fix it quickly.


craig

-- 
craig sanders <cas@taz.net.au>

Fabricati Diem, PVNC.
 -- motto of the Ankh-Morpork City Watch