In some rare cases, you may need to reach out to Mailgun support to remove our IP addresses from a Real-time Blocklist (RBL). This workflow will cover how to verify and resolve these issues.
If a customer is reporting that they are not receiving a confirmation email, you'll want to go through the confirmation email workflow first. When in the Mailgun panel, check for a suppression.
In the logs, if you see a mention of a rejection due to abuse or explicit confirmation of a blocklist, proceed to the link and look up the IP address. Every provider will be different, but if a lookup database is available, you should verify that it is listed and if a reason is stated.
"delivery-status": {
"tls": true,
"mx-host": "mx1.external-mailserver.com",
"attempt-no": 1,
"description": "",
"session-seconds": 1.7985761165618896,
"code": 550,
"message": "5.7.1 H:M11 [192.237.158.143] Connection refused due to abuse. Please see http://mailspike.org/iplookup.html or contact your E-mail provider."
You can confirm that the IP address is ours by doing a "host" lookup on the IP address. It should always end in mg.gitlab.com.
> host 192.237.158.143
143.158.237.192.in-addr.arpa domain name pointer do158-143.mg.gitlab.com.
Navigate to Mailgun > Support and click "Create Ticket". Be sure to include:
Be sure to follow up with the customer and let them know that we've requested support through Mailgun. They should return a response within 24 hours. If we are blocklisted due to a specific account, please check in with Site Reliability Engineers in #production.