Email Related Issues
If you can't seem to send out emails successfully from the software, first go to the "Server Checker" under System Related Options in the AdminCP and run the mailing test:
If it fails, you can check the error log
and see if there is any error recorded.
If the error says something regarding authentication failure, check the "Email Settings" under Basic Configuration and make sure your SMTP authentication username and password are correct, then run the server checker again.
There could be other types of email problems, too.
In APG vNext, we have a mail log viewer in the AdminCP. It will show you whether a mail is generated by the server and whether it was delivered successfully. You can use it in combination with the error log to determine if only certain types of email fail.
You can turn off mail log for performance reasons. Open ~/config/appSettings.config and set EnableMailLogging to false.
Here are some IIS SMTP related questions and answers
I recorded over the years. Check them out if you're using the pickup directory
option to send email.