Problem:  Office365 IP range - is on's blocklist

For some reason, -many- Office365 IPs in the range are on's blocklist.  Since RBLs are checked before any part of the message is sent, these messages are rejected.  Allowing sending email address / domains -does not- get past the RBL Check

From investigation, this has been occurring since about Wednesday, 03 Jan, 2023.

Recommended action:

To get around this, either:

- Remove from your list of RBLs in System Setup > Mail Relay > IP Controls > RBL Servers:

* or *

Add to System Setup > Mail Relay > IP Controls > Bypass RBL Checks


In the logs, you will see something similar this to:
- the NDR the sender gets will see similar

Jan  7 14:04:54 mx1-emailcloud3 postfix/smtpd[16415]: NOQUEUE: reject: RCPT from[]: 554 5.7.1 Service unavailable; Client host [] blocked using; Blocked - see; from=<> to=<> proto=ESMTP helo=<>

If you click on the URL, you will see -many- IPs in the same range being blocked