Linode: Ubuntu 12.04 LTS 64bit
hostname: maestro.visualsymphony.net
domain: visualsymphony.net

As I'm sure you figured out, I'm trying to configure my linode for email. I started out using the guide Email with Postfix, Dovecot and MySQL on Ubuntu 10.10 (Maverick). Once I hit some errors and things weren't working out like the guide explained I hit the forums and found the more applicable but not finalized guide Email with Postfix, Dovecot and MySQL on Ubuntu 12.04 LTS (Precise). I made the changes marked up in red, however I am still getting several errors and unable to get email services running on my linode. Needless to say, I am quite the n00b when it comes to working in this environment, so even properly troubleshooting my issue is beyond the scope of my experience.

I had quite a few errors in my /var/log/mail.log file. I cleared the file and then attempted a mailx info@visualsymphony.net which resulted in adding the following to the log:

root@maestro:~# cat /var/log/mail.log
Aug 24 14:59:01 maestro postfix/pickup[8190]: 7A1E91F8CA: uid=0 from=<root>
Aug 24 14:59:01 maestro postfix/cleanup[8325]: 7A1E91F8CA: message-id=<20120824185901.7A1E91F8CA@maestro.visualsymphony.net>
Aug 24 14:59:01 maestro postfix/qmgr[8191]: 7A1E91F8CA: from=<root@maestro.visualsymphony.net>, size=375, nrcpt=1 (queue active)
Aug 24 14:59:01 maestro dovecot: auth: Fatal: Unknown database driver 'mysql'
Aug 24 14:59:01 maestro dovecot: master: Error: service(auth): command startup failed, throttling
Aug 24 14:59:01 maestro postfix/pipe[8330]: 7A1E91F8CA: to=<info@visualsymphony.net>, relay=dovecot, delay=0.07, delays=0.03/0.01/0/0.03, dsn=4.3.0, status=deferred (temporary failure)

I think I got all mixed up during the process because sometimes the guide would say to use example.com and sometimes it would use server.example.com and I was never sure what I should enter. I would enter my domain (visualsymphony.net) for the former, and my hostname (maestro.visualsymphony.net) for the latter, but I was never confident I was entering the correct data.

Also, some points to note are I have been unable to successfully execute telnet localhost pop3 and telnet localhost 25 / ehlo localhost as per the guide. In both instances I get the following:

root@maestro:~# telnet localhost pop3
Trying 127.0.0.1...
Connected to localhost.localdomain.
Escape character is '^]'.
-ERR Disconnected for inactivity.
Connection closed by foreign host.

root@maestro:~# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.localdomain.
Escape character is '^]'.
Connection closed by foreign host.

And yes, I have opened the respective ports in /etc/iptables.firewall.rules.

Please let me know what else I can do to troubleshoot this further as well as any additional information and/or log files I should post. Any help in this matter will be greatly appreciated.

Also, after clearing the /var/log/mail.log file again and then executing service dovecot restart the following is posted to the log:

root@maestro:~# service dovecot restart
dovecot stop/waiting
dovecot start/running, process 8601
root@maestro:~# cat /var/log/mail.log
Aug 24 15:45:19 maestro dovecot: master: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill)
Aug 24 15:45:19 maestro dovecot: log: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill)
Aug 24 15:45:19 maestro dovecot: master: Dovecot v2.0.19 starting up (core dumps disabled)

That is a normal start/stop output. It was killed properly and then started up properly. What seems to be the problem, I couldn't figure it out from the original post. I may be silly though.

EDIT: Also, I noticed you don't have an A or AAAA record for maestro.visualsymphony.net. You should have one that points to that servers IP address(es). This isn't immediately relevant, but it will be later.

One more thing, for the sake of clarity, I have the linode configured as a LAMP server and all seems to be functioning in that regard. http://www.visualsymphony.net/ is being served correctly, so I don't think I screwed up DNS settings or anything outside the scope of the guides I mentioned using.

I think the main problem is I don't know what the problem is.

The guide has you execute several commands to confirm things are working, but none of them are for me.

telnet localhost pop3 -> fail
telnet localhost 25 -> fail
mailx info@visualsymphony.net -> fail

haha I think that makes it difficult for both of us

Anyway, The only error I see is that it can't find the MySQL database driver. Install dovecot-mysql (apt-get install dovecot-mysql) and see if that fixes anything.

I created an A and an AAAA record for maestro.visualsymphony.net. Thanks for pointing that out. It took me a few tries to get the LAMP set up. I don't want to rebuild the linode and start from scratch if I can avoid it. I am tired of installing and configuring apache/php/mysql.

OK, that may have been it. I installed dovecot-mysql, emptied the log file, ran mailx info@visualsymphony.net and got the following:

root@maestro:~# mailx info@visualsymphony.net
Cc:
Subject: werewr
seghgfhgfjfgj
root@maestro:~# cat /var/log/mail.log
Aug 24 16:09:03 maestro postfix/pickup[8487]: 6CE161F8D6: uid=0 from=<root>
Aug 24 16:09:03 maestro postfix/cleanup[8736]: 6CE161F8D6: message-id=<20120824200903.6CE161F8D6@maestro.visualsymphony.net>
Aug 24 16:09:03 maestro postfix/qmgr[8488]: 6CE161F8D6: from=<root@maestro.visualsymphony.net>, size=381, nrcpt=1 (queue active)
Aug 24 16:09:03 maestro postfix/pipe[8741]: 6CE161F8D6: to=<info@visualsymphony.net>, relay=dovecot, delay=0.07, delays=0.02/0.01/0/0.04, dsn=2.0.0, status=sent (delivered via dovecot service)
Aug 24 16:09:03 maestro postfix/qmgr[8488]: 6CE161F8D6: removed

I already got frustrated once I realized the process was slightly different for my version of Ubuntu from the guide I was using and painstakingly unistalled everything I had done and then began installing everything again a second time with the proper guide. I guess I missed dovecot-mysql the second time around. Thanks for pointing out what seems to be a very obvious mistake in hindsight.

In 10.10 it was all bundled into dovecot-common. Now it isn't. It is easy to overlook. Glad I could help!

Working fine now, the mailbox for "info" has been setup under "visualsymphony.net" and there's mail in the inbox. I will go back over the 12.04 guide to confirm whether or not it was my mistake or the dovecot-mysql reference is missing, and if so, post a suggestion to add it. Thanks again for your help!