| I had an IP reputation issue and managed to resolve it after some time. TLDR: Before you spin up a mail server, check if your IP address is on any of the blacklists [0]-[1] as well as Proof Point's list [2]. If it is, then try and get a different IP address. I spun up a hosted server on Digital Ocean and received an IP address. I checked several black lists from a few email testing/troubleshooting sites [0] and [1] and all was groovy; my IP address wasn't on any list. I got a bunch of 521 bounces when I tried emailing a neighbor who had an att.net address. So, I checked the troubleshooting websites, and my IP address was listed as clean. My logs said I should forward the error to abuse_rbl@abuse-att.net, so I did. Those emails were never delivered, because abuse-att.net had its own blacklist. I was getting 553 errors. In the logs, the message from their server told me to check https://ipcheck.proofpoint.com. Proof point runs their own blacklist that some enterprises use (e.g. att and apple [3]). I checked their list, and lo and behold, my IP address from Digital Ocean was blocked [2]. Digital Ocean wasn't able to remove the IP address from their blocklist and suggested I spin up a new droplet with a different IP address. I didn't want to do that, so I sent Proof Point an email that went unanswered; the email asked them to remove my IP address. I forgot about the issue for five or six months (this is a personal server), and ran into the issue again a few months ago. So I sent Proof Point an email again, this time with different wording emphasizing that "my clients" were having delivery issues. Within a day, they removed my IP address from their block list. So, my main suggestion is to check if your IP address is on any of the blacklists as well as Proof Point's list before you start on your server. If it is, then try and get a different IP address. Does anyone have more "enterprise" lists, like Proof Point, to check? [0]: https://www.mail-tester.com/ [1]: https://mxtoolbox.com/blacklists.aspx [2]: https://ipcheck.proofpoint.com [3]: https://www.reddit.com/r/email/comments/6toxzr/ip_blocked_by... |