I meant the output might help explain it to me! 😀

It didn't. I suppose your SQL Server team might have hacked sp_send_dbmail - the default procedure has an EXECUTE AS 'dbo' on the procedure, but an EXECUTE AS CALLER wrapped around the bit that attaches the file.

I wonder if they have changed that to EXECUTE AS SELF/OWNER/a user mapped to a windows login and removed the EXECUTE AS CALLER bit...? Wouldn't be supported, but it's an interesting idea. I might try it later just to see.

Paul