Delete Old Gmail

• Open Gmail
• In the search bar, if you type older_than:6m, Gmail will list your e-mails older than six months. You can use y for years or d for days, as well.
• If you want to delete all of these e-mails, click the Check all box, followed by the Delete button.
• This moves your selected messages to the Trash. To permanently delete these messages you need to go to the Trash folder and click: Empty Trash Now. (Messages that have been in Trash more than 30 days will be automatically deleted.)

As a best practice you should never store messages older than 180 days (6 months) in your e-mail account (including in the Trash). The content of e-mail older than 180 days is considered a "stored communication" and does not have the same protection under the law as newer unopened e-mail.

Once you have deleted your e-mails and emptied the Trash folder your messages are gone, but there is one more important thing to consider. Residual copies of deleted messages and accounts may take up to 60 days to be deleted from [Google] servers.

According to Google - "Google keeps multiple backup copies of users' emails so that we can recover messages and restore accounts in case of errors or system failure, for some limited periods of time. Residual copies of deleted messages and accounts may take up to 60 days to be deleted from our servers. Deleted messages may also remain on offline backup systems for some limited period of time. This is standard practice in the email industry, which Gmail and other major webmail services follow in order to provide a reliable service for users. We will make reasonable efforts to remove deleted information from offline backup systems as quickly as is practical."

Generally, once you have read and replied to an e-mail (once the e-mail conversation is over) you should delete that e-mail (under 18 USC 2703, opened e-mail stored on a remote system only requires a subpoena to compel your service provider to turn it over to the government). If you think you will need the e-mail for reference in the future, save it to a secure, encrypted folder on your computer (a warrant is required to seize information stored on your home computer). To avoid having "stored communications" in your Gmail it is important that you delete opened e-mail as soon as possible after reading it, and all messages older than four months (this allows for residual copies to exist on Google servers for up to 60 days, yet still be permanently deleted before becoming 180 days old).