Google password required at each startup

Hi,

I recently reinstalled Yosemite, and since I added my three gmail accounts in Mail, at each startup all these Google accounts are asking for my passwords.

I checked in the keychain, fixed permissions, removed all passwords, added them again... To no avail.

Please note that if I don't enter the passwords, my emails work just fine, but it's quite annoying nonetheless.

Anyway thanks in advance for your help!