My database has a standard of spitting files out in .xls format -- and I'd imagine because it's outdated, since I've upgraded to Excel 2016, I now get this every time I attempt to open it:

Alert

The file format and extension of 'test.xls' don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?

Then I hit yes and everything opens/works fine. But it messes with my automator and other script I run, which makes it very annoying. Does anybody know a way to turn this alert off, or how I can tell Excel that I will always trust its source?