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.
Check for Suppression in Mailgun
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.
Verify the RBL listing
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.
Open a Ticket With Mailgun
Navigate to Mailgun > Support and click "Create Ticket". Be sure to include:
The IP Address that is blocklisted
The name of the RBL and link to it (Found in the Message returned by the mail server)
Copy of the Logs
Follow up
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.
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