Adding MIME types in SharePoint Online


I've got a user looking to store .oft files in a SharePoint Online document library, and they were expecting to be able to open them inline. Instead the only option is to save the file. I'm guessing that it's because the .oft extension doesn't have a mapped MIME type, and so it's falling foul of the 'X-Download-Options' header.

If this was on-premise, I'd be either looking to add the MIME type in to the IIS server (best case), or setting Permissive mode on the farm. As I can't get that deep into the SPO stack, is there any alternative here, or should we go back to the drawing board?



Hi Steve,

You are correct that the .oft file extension does not have a mapped MIME type in SharePoint Online which is causing the file to only have the option to be saved. Unfortunately, there is no alternative in SharePoint Online to change this behavior.

Given the situation, we suggest you submit your idea via UserVoice; this is the best way to influence our products and services to make it better for you and others.



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Last updated July 3, 2020 Views 1,602 Applies to: