MacBook Pro 15inch Retina 2015 i7 2.2Ghz/16GB RAM/256GB SSD El Capitan 10.11.6 Hey guys hoping someone can help me out here. Ok so everything was working fine until I decided to upgrade to Siera - but my work applications didn't work too well with it so I then had to revert back to El Capitan with a clean install. I've set everything up as it was and the only problem I'm having is adding my gmail account to mail. I also have my iCloud account signed in and that works fine. No matter what I do mail will not sync my gmail and won't even allow the account to show in mail>prefs>accounts (iCloud is there). This is what I've done so far with no resolution: - Added gmail account to internet accounts (system prefs) and ticked mail. Removed account and then added it back in - still no luck. - Removed gmail account, loaded mail, mail preferences>accounts and then added gmail in here. No luck - it goes throguh the process but when I add the account it just disappears. - Restarted machine. No luck. Gmail shows up fine in my internet accounts but will just not show up in mail accounts no matter what I do. Has anyone ever had this issue and does anyone know what I can do to resolve this? Thanks in advance.