Problem
You're getting an Unauthorized IP address notice on Teams notifications.
Solution
As a workaround, a rule can be added to the Exchange Admin Center in Office 365 to allow voicemail messages from Microsoft. To create this rule:
1. Navigate to Exchange Admin Center > Mail Flow > Rules
2. Click on "Create a new rule"
3. Create a new rule that:
Name: Teams Bypass
Apply this rule if: "The message type is"> include the message type > "Voice Mail"
and Sender's IP address is in the range "20.0.0.0/8, 13.107.64.0/18, 52.112.0.0/14, 52.120.0.0/14, 52.238.119.141/32, 52.244.160.207/32, 2603:1027::/48, 2603:1037::/48, 2603:1047::/48, 2603:1057::/48, 2620:1ec:6::/48, 2620:1ec:40::/42"
[please check Microsofts documentation for their latest Teams IP addresses - see https://docs.microsoft.com/en-us/office365/enterprise/urls-and-ip-address-ranges]
Do the following...
"Require TLS Encryption"
Chose a mode for this rule: Enforce
Check "Stop processing more rule"
4. Click Save
5. Ensure the completed rule is placed above the Proofpoint block rule (the rule needs to be at the top of the list of rules).
The completed rule will look like:
