Well, it’s me again,
What a rollercoaster of emotions! So, I think I’ve fully resolved it (it terrifies me to say that). So, for anyone who may be experiencing a similar issue and this thread is TL:DR here is what happened…
I was running WP Mail SMTP to bolster my wp_mail()
function. I found that when I used the “TEST EMAIL” button via the WP Mail SMTP settings it sent through to any mail address I tried. But when I tried to input any address into the wp_mail()
function it only sent to Gmail and Exchange, but not others.
So, after trying Mailgun and pointing DNS records all sorts of which ways, and then deciding to leave Mailgun (because it didn’t change anything), then speaking for hours with my ISP, I arrived at the same place I’d started at. So I tried something else; deactivate the WP Mail SMTP plugin and try and reconfigure the PHP Mailer settings through the `phpmailer_init’ hook. That didn’t work either.
Those familiar with the plugin will know that when setting up you choose what type of mailer you use; PHP, Google, Mailgun, Sendgrid, Other SMTP. Other than my little Mailgun excursion I had chosen “Other SMTP”. The reason I did this was because (I think) that when setting up mailboxes through my ISP, the type of mailbox I had to choose was always “Other”. Human logic.
*NB PART* : So, I changed the type of mailer to PHP (the first option in the plugin’s settings) and everything works. No matter what address I plug into my wp_mail()
function it goes through.
I hope this helps anyone who finds a similar problem. Save yourself two weeks of angst!
Thank you Slava for the help, and the plugin. It is not faulty, I’m just a faulty human… or just a human. Good luck all!