Mailgun’s plugin works, yours doesn’t, same credentials

Replies: 0

I have two domains, one which sends transactional mail via Mailgun’s “outdated” plugin, with no problem, the other on which I use WP SMTP MAIL and can’t get to send, for some reason.

As a test, I installed the old Mailgun plugin with the exact same credentials and it worked immediately.

What’s wrong with your or misconfigured with your plugin?

Versions:
WordPress: 4.9.4
WordPress MS: Yes
PHP: 7.0.28-1+ubuntu16.04.1+deb.sury.org+1
WP Mail SMTP: 1.2.5

Params:
Mailer: mailgun
Constants: No
Api Key / Domain: Yes

Debug:
Forbidden