Unfortunately I've used POP3 to synchronize my mails from www.gmx.ch with Thunderbird Mozilla Firefox (incoming mails: pop.gmx.net port 995) and (outgoing mails: mail.gmx.net port 465). The box delete mails from Server after 14 days has been checked. Now almost all mails from the server has been deleted. Is it somehow possible to transfer the mails backwards to the GMX-Mail-Server?
I don't think if there could be any solution to this. IMAP account takes a copy of emails to the locations configured. However, POP accounts simply moves them permanently. Deletion is therefore permanent.
We are offered a limited space in our office. Exceeding that space leads us to a fine. We have therefore configured our accounts through POP. The mails download to our local servers. To avoid deletion and hardware crashes, we have backed them up to DropBox through Mail Backup X. That helps us in many ways.
Mail Backup X: http://www.mailbackupx.com/download.html