Configure VERP to handle bouncing e-mails

[nathank (Nathan Kershaw)]

Updated the Mailgun section as things have changed a wee bit in their UI:

@zogstrip

MailGun

1. Log in to MailGun and go to your dashboard ; look in the left column for the Sending → Webhooks page.
2. Make sure that the correct Domain is selected (top right on desktop)
3. In Discourse, set the mailgun api key site setting with your HTTP webhook signing key
4. Click the Add webhook button, set the “Event Type” menu to “Permanent Failure”, and set the URL to https://your.discourse/webhooks/mailgun
5. Repeat the Add webhook portion, choosing “Temporary Failure” as the “Event Type”
   • there is a “Test webhook” section which is useful for testing, but doesn’t save - make sure you use the Add webhook button instead