Cannot send emails using Sendgrid on Heroku Cedar stack

Question

I receive the following error: 451 Authentication failed: Maximum credits exceeded.

However when I check the sendgrid dashboard on heroku it says:

Is the dashboard outdated? It says I still have remaining credits...

Impromptu

you should open up a support ticket on this one. support.sendgrid.com. Also, I would double check that you're using the right credentials. – Baty

I talked to customer support from Sendgrid. They told me to get in touch with Heroku. I followed this tutorial from Heroku to set up the email service in the first place and it was working until 5 days ago. devcenter.heroku.com/articles/sendgrid#ruby-rails – Impromptu

And if you type heroku config, are SENDGRID_USERNAME and SENDGRID_PASSWORD assigned the correct values? – Baty

Its best just to use SendGrid directly, without the add on. Alternatively, MailGun has a better integration with Heroku – Stephanistephania