According to existing law - your email stored on any Cloud Email Service Provider (Gmail, Hotmail, Yahoo, etc.) can be accessed after 180 days without any court order or subpoena. Unlike letters and hard documents which would require "due process" electronic email is NOT covered by the existing laws in the United States. Government agencies have free access to everything after 180 days. There are several laws pending to overturn this situation and make ALL your documents protected by the same laws that protect letters and hard documents. Until then your email on these various services are considered "public" and they are accessed, copied and stored by various government agencies at the 180 day mark. After that, even if you remove the email from the service it will may not be removed from the government copies.
Our TeleSites.net Email Servers are NOT within this public Cloud storage system. We own our own cloud. The government would have to request access through legal channels to see any electronic messages stored on our email servers. To date they have not.
That said it is always a good policy to delete any email stored in any free or paid accounts on any of these "public" email services. Keep in mind that many of the Cable Internet and Smartphone Service Providers (email addresses that end with @att.com, @comcast.com, @verizon.com, etc.) may also allow broad access to their Email Servers.
Most all of these providers allow you to download your older emails onto your own computer before you delete them. Easiest way to find instructions is to do an Internet search of your provider's name and "export email."
Hint: To delete email older than 140 days in Gmail - Log into Gmail and do a search with this phrase: older_than:140d If you select the ALL check box above the messages - then you will see a link to "Select all conversations that match this search" - then click Delete. This will move the message to the Trash folder - don't forget to empty it too.