Maximum entries Spam filter allow list

Copper Contributor

I work at a school and we have a Spam filter policy activated in Exchange Online. We notice that sometimes some emails from parents are seen as bulk mail. By adding them to the allow list of the spam filter policy, all mails from that parent comes through. But I want to prevent this from happening ever again with any parent by adding all registered addresses of parents to the Spam filter policy Allow list. It looks like I hit a maximum of 1024 entries since I was trying to add over 2200 addresses.


How can I achieve the same in another way? Or can I raise the limit of the Allow list somehow?

2 Replies
best response confirmed by Randolf Broer (Copper Contributor)
Correct, exchange online protection limit for Allow List is 1024 entries.

You could

1.) Shrink the list by identifying similar domains and add the domain instead of each individual addresses
2.) Do the same for IP's for well known services (I.e. Outlook, GMail)
3.) Consider a third party gateway with a higher allow list

AFAIK there is no way to raise this limit. There is a uservoice open for this, but looks like its been some time and not been picked up.

Hope that answers your question.

Best, Chris

Something else you can try is to add them to "bypass spam filtering" Transport rule, however there are limits there as well. Maybe change the default "bulk" action to quarantine, and then review the quarantine at regular intervals to release any parent's messages?