Some time ago, Sendgrid had a security breach which I THINK affected the company I am working for. Right now, emails sent to popular email servers like outlook are not arriving at the customers. Sendgrid tells me the emails are getting blocked. This is different than being marked as Spam, because the email does not even end up in their spam box.

There are links to services like Spamhaus (Which, as I understand, protects users by blocking email before it reaches them) that blocked the email.

My questions:

  • Sendgrid/Spamhaus mentions an IP address that is blocked. Can you guys tell me if this is the IP address that sendgrid uses (as our codebase doesn't send emails; we just defer this to Sendgrid), or if it is the IP of our emailaddress or something? I have not a lot of knowledge when it comes to email :).

  • What is the best way to fix this ASAP? Spamhaus says to talk to Sendgrid/ISP, but Sendgrid isn't responding to issues. I am guessing all I can do is just reach out to every spam protecting service and ask them to remove that IP address, but that can be a lot of manual work.

I found some other threads about my problem but none were really able to help me out because my problem is not truly of a technical nature or misconfiguration, I believe. Nothing in our mail or mailing strategy changed to warrant such email blockage.

Thanks everyone!

  • 2
    It would help if you could provide the exact messages Sendgrid/Spamhaus are throwing, especially if they include the IP address in question. – ceejayoz Sep 18 at 13:03
  • This is one reason I'm dissatisfied with Sendgrid. They don't seem to notice when their IP addresses get blacklisted, and they just blindly keep trying to deliver mail via them instead of taking them out of rotation and cleaning up. This is their job, not yours. It's literally what you're paying them for. – Michael Hampton Sep 18 at 17:15
  • @ceejayoz An example: 550 5.7.1 Service unavailable, Client host [IP_ADDRESS] blocked using Spamhaus. To request removal from this list see spamhaus.org/query/ip/IP_ADDRESS AS(1440) [DB5EUR03FT048.eop-EUR03.prod.protection.outlook.com] an example URL (not mine, I dont want to expose any private info) spamhaus.org/sbl/query/SBL495495 – S. ten Brinke Sep 20 at 12:27

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