Check if your mail server supports IMAP and if it does you can
switch your account from POP3 to IMAP and then upload all your
mesages back to the folder on your server. And you can also switch
all other accounts on your IMAP and then you will be checking your
email right on the server. And its not going to go anywhere from
the server. Its going to have a copy on your local computer but it
will also leave a copy on your server. Thats how gmail works and
thats how yahoo works.