sendmail confusion and solution (a back-story)

[Metatron]

Hy I just want to share a solution for a specific problem with the ispcp requirements and their configuration.

courier and postfix are recommended (if not even required, I don'T rememeber). In the newest version (and maybe older ones too) of courier, courier itself comes with sendmail in addition. Which means you got three sendmails:

courier, posfix, sendmail.

My system is fedora and has (like maybe others too) the alternatives command to choose between the different MTAs. Now by default the choice is 'auto'. I don't know if there is a priority system behind or if it's order of installation.

I now got problems sending mails via 'sendmail' only, sending from outside was without issue. Well it's not quite clear from outside if my installation order caused the courier sendmail to be the choice on auto; but after migrating my system from FC4 to FC9 I couln'd use the 'sendmail' anymore. This was the error:

May 7 02:02:24 host148 courierd: newmsg,id=0002C3A2.4A027970.00007247: dns; localhost (localhost [127.0.0.1])
May 7 02:02:24 host148 courierd: started,id=0002C3A2.4A027970.00007247,from=<vu2004@host148.hostinganddesign.com>,module=esmtp,host=adsignum.com,addr=<spamtrap@adsignum.com>
May 7 02:02:24 host148 courierd: Waiting. shutdown time=none, wakeup time=none, queuedelivering=1, inprogress=1
May 7 02:02:24 host148 courieresmtp: id=0002C3A2.4A027970.00007247,from=<vu2004@host148.hostinganddesign.com>,addr=<spamtrap@adsignum.com>: configuration error: mail loops back to myself (MX problem).
May 7 02:02:24 host148 courieresmtp: id=0002C3A2.4A027970.00007247,from=<vu2004@host148.hostinganddesign.com>,addr=<spamtrap@adsignum.com>,status: failure

Well after simply not accepting that my courier or postfix configuration was wrong, I continued digging untill finding the alternatives command. And that shows this:

> alternatives --config mta

There are 3 programs which provide 'mta'.

Selection Command
-----------------------------------------------
1 /usr/sbin/sendmail.sendmail
2 /usr/sbin/sendmail.postfix
*+ 3 /usr/lib/courier/bin/sendmail

Great, I switched to 2 and all was fine.

So much about this little back-story. The conclusion is, if you get courieresmtp errors, you havn't made anything wrong, the system just doesn't use postfix.

I hope I made no errors in the explanation, I'm no die-hard admin.
Maybe one day we may have the switch in the installation routine of ispCP.

Saludos
Niels