Automated removal of specific attachments from incoming emails

Copper Contributor

Hello all,


I'm bringing this discussion here, as it was something that was requested on Uservoice, but the Exchange uservoice site no longer exists.


My pain is Exchange Online not having the option to automatically remove an attachment using a flow rule. It know it would be possible to have a "blanket" removal of attachments using EOP, but there I cannot select, for example, .txt extension to be filtered out.


The company I work for has partners that automatically add a disclaimer.txt attachment to any email leaving their servers.  Some of my bosses would like to be able to search for "the email from that guy that has an attachment", and it's pretty hard when all of them have attachments.


I was trying to use rules, I can target the emails coming from that domain that have the disclaimer.txt attachment, but I have no option to remove that attachment. I tried all kind for power automate options, but nothing helps. In the end, most likely we'll have to use a 3rd party Outlook plug-in for that, but I think it would be a much more elegant solution to have this option on the server side, as a flow rule.


I know this was a request on uservoice, it had some hundreds of votes, but as the site no longer exists, I am not sure what would be the status for that request. 


Or is there some way to achieve this with the current options? I couldn't find any.


(my bosses even agreed to a blanket removal of all .txt files from their emails, tried to achieve it using EOP to block that specific extension, but it's not on the list of aprox. 100 extensions that can be blocked.)

2 Replies
You should be able to exclude specific attachment types from your searches, so just use that? Mail flow rules wont help here, as there is no such action. You can try adding it to the common attachment filter via PowerShell (Set-MalwareFilterPolicy).
I tried adding it to the common attachment filter in a new policy, however the emails are completely quarantined, even if the action I configured is to DeleteAttachmentAndUseCustomAlertText. I think this was changed earlier this year or late last year, that the emails are no longer delivered with the attachment removed, but quarantined. Or is there some hidden configuration option that I couldn't find?
I still think that would be great to have the option to this filtering using mail flow rules.