Date: Tuesday, June 16, 2015 07:21:06 PM -0400 From: Steve Matzura number6@noisynotes.com
On Tue, 16 Jun 2015 22:02:29 +0200, you wrote:
Am Dienstag, den 16.06.2015, 11:44 -0400 schrieb Steve Matzura:
The next phase of my testing procedure involves the simple act of delivering mail to my test box. When I send a message to either a valid or relayed user at my remote machine's address, it never gets there. I know this virtually for sure because I'm tailing /var/log/maillog and nothing new has been added for the past hour. I'm thinking eventually my ISP will send the message back to me as undeliverable, and in that bounced message there may be some information about why it was undeliverable, but maybe someone has a thought as to why I'm not even seeing anything attempt to connect?
Receiving and Sending Mail is done by the MTA like postfix or exim. Not Dovecot. It's just for the IMAP/POP access by the users to get the mails. So look at that logs. And if there's nothing in it, then make sure port 25 is actually open by the postfix/exim process.
Well, it isn't. In fact, there is no exim process running. However, something calling itself 'master' has port 25 open according to netstat, and that process has a subprocess running something called qmgr. I'd give more information, such as path to these programs, but it isn't shown. Time to check my Postfix config a little more closely.
Those pieces are all part of the postfix MTA (you haven't indicated your OS, but postfix is the current default on most current linux distributions).
As I indicated earlier, by default most (current) MTA installs only listen on localhost, not on the external interfaces, so don't accept off-host mail.
There is extensive postfix documentation and also a postfix mailing list if you need assistance.