Hi and welcome to mobileread
As your question is very specific to Calibre, you might get a better response in the Calibre forum here on mobileread:
https://www.mobileread.com/forums/forumdisplay.php?f=166
I don't think sending a feed wirelessly via your Kindle email address will alter having a failed feed - it just means that it delivers the feed to your Kindle which can pick it up when connected rather than plugging your Kindle in via the USB.
I guess it could be to do with some settings or it could be a problem with the feed itself. Hopefully you'll get the problem solved.
I do have a page on setting up Calibre with feeds but I don't think it will resolve your particular problem, just maybe to check it is set up correctly:
http://www.kinworm.com/2010/10/addin...n-calibre.html