from gmail.google.com/gmail/he… :

"Email contents and usage. The contents of your Gmail account also are stored and maintained on Google servers in order to provide the service. Google’s computers process the information in your email for various purposes, including formatting and displaying the information to you, delivering targeted related information (such as advertisements and related links), preventing unsolicited bulk email (spam), backing up your email, and other purposes relating to offering you Gmail. Because we keep back-up copies of data for the purposes of recovery from errors or system failure, residual copies of email may remain on our systems for some time, even after you have deleted messages from your mailbox or after the termination of your account. Google employees do not access the content of any mailboxes unless you specifically request them to do so (for example, if you are having technical difficulties accessing your account) or if required by law, to maintain our system, or to protect Google or the public. "

"we log this information for internal business purposes."

"We reserve the right to transfer your personal information in the event of a transfer of ownership of Google, such as acquisition by or merger with another company."

" You can terminate your account at any time, by going to the account information page. We typically deactivate accounts within two business days of such requests. You should be aware, however, that residual copies of information may remain stored on our systems even after the deletion of information or the termination of your account."