Spamhaus have released their guidelines for senders.
It’s very clear, very precise and generally very good.
Overview: https://www.spamhaus.org/resource-hub/deliverability/spamhaus-sender-guidelines/
For senders: https://www.spamhaus.org/sender-guidelines/
For ESPs and large senders: https://www.spamhaus.org/sender-guidelines/esp-large-senders/
Dear Colleagues at ESPs,
We have a problem. More specifically, YOU have a problem. You have a spam problem. One that you’re not taking care of in any way, shape or form.
Read MoreMuch of the current deliverability advice focuses on a few key ideas:
Read MoreAn on the ball reader sent me a note today showing a bounce message indicating microsoft was rejecting mail due to a Spamhaus Blocklist Listing.
5.7.1 Client host [10.10.10.10] blocked using Spamhaus. To request removal from this list see http://www.spamhaus.org/lookup.lasso (S3130). [VE1EUR03FT043.eop-EUR03.prod.protection.outlook.com]
The IP in question is listed on the CSS, which means at a minimum Microsoft is using the SBL. I expect they’re actually using the ZEN list. ZEN provides a single lookup for 3 different lists: the SBL, XBL and PBL. The XBL is a list of virus infected machines and the PBL is a list of IPs that the IP owners state shouldn’t be sending email. Both of these lists are generally safe to use. If MS is using the SBL, it’s very likely they’re using the other two as well.