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The original was posted on /r/sysadmin by /u/DoorDelicious8395 on 2024-01-23 15:57:23+00:00.
We have a on premise smtp relay server(postfix) that is used to route emails from our ERP system and various printers to the internet. The relay is setup to forward all of our emails to our exchange online smtp connector using ip auth. Well today exchange is replying to all emails with 550 5.7.1 Service unavailable, Client host [xx.xxx.xxx.xxx] blocked using Spamhaus. To request removal from this list see https://www.spamhaus.org/query/xx.xxx.xxx.xxx Our ip is owned by comcast but is an enterprise plan.
Does anyone have any recommendations on getting around the ip blacklist so we can forward them to our exchange connector?
Update
I opened a case with Comcast and the technician told me that he had 5 of these cases open this morning with the exact same issue. He mentioned that it was an issue on their end.
Either way I should move away from IP auth in exchange as there are more secure alternatives. Thank you everyone for the suggestions.