Using Classic Outlook on Windows for personal email, calendar, and contact management
Thank you for checking that. I see that we have a bug with signatures for catch all scenario because it introduced invalid filename characters in signature names. That bug is fixed in 16424.10000. The fix should get to Current Channel ~5/29 with version 2305. Or, if you want to test sooner the fix should get to the Beta Channel in the next build that goes there, maybe late this week.