Interesting, my mail to someone using Office 365 was rejected because .odt and .ods attachments are not allowed.
@johns strange behavior as word supports odt files
https://www.quora.com/How-do-you-open-an-odt-file-extension-in-Microsoft-Word
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@AlxndrJhn Yeah, I'm assuming this is justified on "security" grounds, using a "block it all by default and allow only necessary exceptions" approach. My question now is whether this is a default / encouraged filter rule...
