Increased error detection from realtime blocklists

Apparently, the IP addresses of many systems that Microsoft uses to send emails from M365 are currently on a realtime blocklist. NoSpamProxy initially rejects the processing of emails in these cases. Read this blog article to find out what you can do now.

NoSpamProxy often accepts the initially rejected emails in further manual sending attempts by the sender. This is because in these cases the email is sent to NoSpamProxy from a different M365 system and therefore also from a different IP address.

What you can do

In order to be able to receive the emails without the need for further manual delivery attempts by the sender, we recommend a configuration adjustment.

Option 1

For customers with their own (on-premises) NoSpamProxy installation, it is possible to influence the rating of individual realtime blocklists. For example, the penalty points (SCL) assigned by a list can be halved. The option for this can be found under Configuration > Presettings. You can find out more about this in the online documentation under Presettings.

By halving the assigned penalty points (SCL), additional filters are always required, which assign penalty points (SCL) so that the email received by the affected systems would be rejected. In other words, the email is no longer rejected solely on the basis of the entry in the affected real-time block list.

Option 2

Another option is to maintain an allowlist within the rules. You can find out more about this in the online documentation under Creating an allowlist.