News in both Epub and Mobi Format

[Charlie A]

I know how to have recipes output in .mobi and get e-mailed automatically to my Kindle Paperwhite.

I can change preferences to have recipes generate epub that I can fetch from the Calibre content server with my 1st generation Nook tablet.

How do I get Calibre to make news files in both epub and mobi without having to manually initiate the format conversion?

Thanks,

Charlie

p.s. I do realize that with newer Nook tablets the easy solution is to install the Kindle for Android app, but I have a non-rooted older Nook tablet.