I have read some of the posts related to this topic, but I have not been able to apply to recommended solutions.
My hosted web site (porterfieldjunction.net) uses a PHP application called TNG - The Next Generation which is a genealogy application. It includes several functions that can trigger outbound emails to individual registered users or to myself as administrator. None of these emails are arriving at their destination.
The help info for TNG says the following about setting up the outbound email.
Normally TNG sends email by way of the PHP "mail" function. If you'd rather use the Simple Mail Transfer Protocol (meaning that a login must be supplied by the program before the mail can be sent), then set this option to "Yes". More options will then become visible. They are: SMTP host name, Mail username, Mail password, Port number and Encryption. Your hosting provider should be able to give you the correct values for these fields.
I have tried both options. For the SMTP option, I used smtpout.secureserver.net for the SMTP host name, port 465 and SSL encryption.
Thanks for the information about the relay server. However, that did not solve the problem -- it just changed the type of error I received. The application displayed the following error message:
"We're sorry, but your message could not be delivered."
When I use the relay server, should I use my own email user name (address) and password? I used port 465 and SSL encryption. Is that right? I also did a quick test with port 25 and no encryption. That failed also.