In Marketo's next major release (scheduled for May 7, 2021), Marketo will upgrade export capabilities throughout the product to support XLSX in place of XLS. This means that anywhere in the product where XLS export is currently supported, this option will be replaced with an option to export to XLSX instead.
Please take note of the above change as it will affect the file names (by virtue of the .xlsx extension) for all Excel exports of reports and other data from Marketo.
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