Mail sends from Outlook to external email account but never arrives. No errors given

Hi I set up VirtualMin on a clean install of Ubuntu 12.04.4 x64 based on the instructions here: https://www.digitalocean.com/community/articles/how-to-install-and-utili...

I am having trouble with sent messages in Outlook failing to arrive at their external email destinations, regardless of target email. I can successfully receive messages from my ISP supplied email but if I reply back the message never arrives. I dont get any indication that there has been a problem.

In the Virtualmin post-installation wizard I turned most things off to save RAM. I have since disabled Antivirus and Antispam features to help diagnose.

Outlook is configured as follows: Account type: POP3 Incoming: mail.mydomain.net Outgoing: mail.mydomain.net Username: testmail.serveradmin Outgoing server requires authentication. Using same settings as incoming. Incoming 110, outgoing 25

From this forum I followed instructions to do this: "Also, to make sure that SMTPS and Submission are enabled, you can edit your /etc/postfix/master.cf file, and make sure the lines in there beginning with "Submission" and "SMTPS" are uncommented (along with all the lines following them that begin with "-o". Then restart Postfix after making any changes to those."

I have tried to access mail log files using Filezilla, but when I go to var/log/virtualmin I get 550 Permission Denied, which is odd since I am logged in with the administrator account, and I cannot change permissions on the folder without having permissions to start with.

I also read that there is some kind of log viewer functionality in Virtualmin but under Logs and Reports I only have the following, so I dont know where to go after that: AWstats Configuration, Apache Access Log, Apache Error Log, Logged Webmin Actions, View AWstats Report, Webalizer Report

Any tips would be much appreciated.

Thanks!