Good question. I don't think so.I asked the devs about this and while I didn't get a yes/no response here's what I can share:v1.9.4 will ship with ability to accept attachments based on mime types
in addition to file extensions. The setting are no longer global - it's
configurable as part of thread entry field. We've also added
FileUpload field type - meaning users can now add additional independent
attachment fields and configure acceptable files types at the field
level.