> Is gmail secure or can google dip into your account and read the mail?
Can google dip into your account and read the email...I guess YES.
In that sense, anything on the web is readable by web administrators and database admins who are managing that particular server or database.
Only your home desktop is safe, so long no one intrudes into your computer [through internet] or physically.
But, I would say, people do not have time to read their own emails and, it is impossible to read other people's email. Admins are ethical and they have no time to sniff other peoples' emails, even if other people emails are embedded with millions-a-day trading plan.