It seems that MailGun is using some sort of verification if the target email exists.
It also seems that it thinks the email does not exist in 90% of the cases. I was getting multiple errors that email does not exist and then after 10th try it acknowledged the email exists… only to throw more errors that email does not exist afterward.
Sometimes I was able to get “email exists” then retry with the same email address after 15 seconds and get “email does not exist” instead.
And because some websites use MailGun verification before letting create account, I can’t use my mailbox and had to use gmail to register for Epic Games so I can grab that sweet free games.
Obviously I would like to keep using my mailbox so I actually have control over everything but we have to somehow figure what MailGun is doing and how to make changes to the MiaB to make it work together.
I use domain-wide alias to catch all emails to my main mailbox so I can use different email addresses for every service (and then block that email address if they leaked it/sold to 3rd parties for spam). But that doesn’t seem to be an issue - trying to register with created user and existing email causes the same error. I set verbose logging in postfix and it shouldn’t matter because it finds recipent anyway due to virtual mailbox check (@domain => recipent@domain).
I spent good few hours debugging and I have no idea where to go from now. The logs are IDENTICAL for MailGun checks that say “account exist” and for checks that say “account does not exist” except time and ids of course. Do you have any idea what to do now?