Can the government trace an email that has been sent from an account that is now deleted?
Yes. Very simply. The email comes from an email server, and it is very easy to determine which server from each email sent from the account. The server will have logs of that deleted account and its activity. So the government can look at the email, contact the server owner, and ask for the details of the account holder. In some places, such queries are automated.
Just because the user doesn't have access, that does not mean that the email server does not either.
Over time, the old logs and old data might get deleted since it is no longer useful. But one can't predict when that might happen, or even if it does.
3Add to that that any data send to another machine is outside of your controle.... which definetly applies to Emails. and that email headers contain quite a bit of information to identify the sender (the technical sender that is)...– LvBMar 16 at 13:45