For a number of months now, Gmail is constantly marking emails incorrectly as spam, and when I move them back into my inbox, it moves them back into spam again within an hour. It doesn't matter if I drag the emails to the inbox, or if I press the “Not spam” button, it moves them temporarily but then they go right back into the spam folder.
I login to Gmail almost exclusively using Google Chrome on a desktop PC, though I have also got it configured to work via IMAP with my Android phone, and Windows Live Mail on my home PC (that is rarely on).
There are two things that I think could have caused this:
Allowing apps such as Mailstrom to access my Gmail, but access has since been removed via https://security.google.com/settings/security/permissions?pli=1 and I'm still having the same problem. Here are the apps that still have access: http://pastebin.com/CXXPXTMi
I was so fed up with the situation I created a filter to move all of my spam into my inbox, but it didn't work. I have since removed the filter.
I've also tried sending all mail directly to the inbox using this filter with no luck - How can I remove spam filtering in Gmail?
Any suggestions please? This is making Gmail pretty much unusable right now, and whilst I'm tempted to migrate everything to Outlook.com, that is an absolute last resort for me.