Im working on a project with Ruby on Rails language, deployed to Heroku everything is working fine I had Mailgun addon installed in my Heroku app at one point I tried to change it to another mailing Addon so I unlinked the Mailgun addon and connected another Addon after a little research, I wanted to connect back the Mailgun addon.

when I tried to connect Mailgun again, it said that my app has an account and I cant reconnect it I cant access my account by the email written in the Heroku's error notification.

what should I do at this point?

In that link below, there is an image of the error I get in my terminal.

Heroku Error for command: " heroku addons:create mailgun:starter"

Another link for an image of the error I get when trying to add Mailgun addon through my heroku app dashboard. Heroku Error from Heroku dashboard

If you think I should use another mailer addon, I would love to hear about it.

Thank you in advance