How to suppress the file corrupt warning at Excel download?

Question

I have a web page which links to an Excel 2007 worksheet. It is a .xls file and not .xlsx file. When I click on the link I get the usual dialog box

Answer 1

For the old Excel format (.xls)

Assuming you create your spreadsheet object with this syntax:

You would use this to create the download:

For the newer Excel format (.xlsx)

Create your spreadsheet object with this syntax:

And use this to create the download:

Thanks to Raymond Camden for the bulk of this (his example was for creating the spreadsheet in the older format -- I updated for the newer format and use slightly different MIME values).