Unable to send email from primary domain
Currently, I have a Ubuntu 16.04 LEMP stack DO droplet hosting a WordPress site, I'll call the primary domain xyz.com. Email is sent via a contact form on the site. The primary domain's email is being handled by a different server (not managed by me).
I'm having an issue sending emails via the PHP's mail() function which WordPress utilizes. I'm able to send email to any domain (gmail.com, hotmail.com, etc.), however I'm unable to on the primary domain (xyz.com).
I think it has to do with the primary domain trying to stay internal since it's the same domain name at both locations, and it believes xyz.com is local to itself and won't send it out.
I haven't been able to find a solution for this issue. I feel like it's a common issue, but my Google search skills have been lacking.
Any help would be much appreciated!