I need a way to query the sender's email address before delivery is attempted, and then set wp_mail arguments depending on the results.
So something like the following:
- If sender_email contains @domain.com then continue
- Else, if sender_email doesn't contain @domain.com, update wp_mail headers before sending
Use case is basically this:
I'm authenticating domain email using Postmark, so email will only send successfully if the sender's address matches an authenticated domain in my Postmark account.
What I want to do is create a check before it tries to send through Postmark, and if it's not an authenticated email address then send using wp_mail (WordPress's default mailing system) instead.
Or, put another way, ONLY send email through Postmark if it matches a specific domain or email address (which we can set manually).