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Problem: Office365 IP range -40.107.0.0/16- is on bl.spamcop.net's blocklist
For some reason, -many- Office365 IPs in the 40.107.0.0/16 range are on bl.spamcop.net'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 bl.spamcop.net from your list of RBLs in System Setup > Mail Relay > IP Controls > RBL Servers:
* or *
Add 40.107.0.0/16 to System Setup > Mail Relay > IP Controls > Bypass RBL Checks
Symptoms
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 mail-vi1eur05on2128.outbound.protection.outlook.com[40.107.21.128]: 554 5.7.1 Service unavailable; Client host [40.107.21.128] blocked using bl.spamcop.net; Blocked - see https://www.spamcop.net/bl.shtml?40.107.21.128; from=<First.Name@somedomain.com> to=<user@recipientdomain.com> proto=ESMTP helo=<EUR05-AAn-obe.outbound.protection.outlook.com>
If you click on the URL, you will see -many- IPs in the same range being blocked
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