Hello @Michael Shechter ,
Currently there is not an option natively in the settings to restrict the filetypes, only an option to either allow or block attachments.
But for this to become a native feature we are tracking interest in file type restrictions at the following feature request, noting that there are linked feature requests off the main one for both Jira Cloud and Server respectively, make sure to add a vote to the requests per the Implementation of New Features Policy to help track the interest.
As a workaround on Jira Server check out the Attachment Checker for JIRA plugin noted in the Jira Server feature request that adds in this functionality.
Catch up with Atlassian Product Managers in our 2020 Demo Den round-up! From Advanced Roadmaps to Code in Jira to Next-Gen Workflows, check out the videos below to help up-level your work in the new ...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events