@pitaj Thanks a lot : that really makes much more sense now.

I allready had deployed mailgun as a service through the use of an API key and that's what i was looking for !
Now that my domain has been created in the mailgun admin pannel and verified through the propagation of specific DNS records, i can confirm that the SMTP credentials are working and that the mails are being sent !

These clarifications were very helpful indeed ! 👍