yawebmail is a webmail-client written in Java as a webapp. Having it deployed on your Internet-accessed webserver, you can get access to your POP3- or IMAP-Mailbox, even if you are behind a firewall that blocks the eMail-ports - in general port 25 for SMTP, port 110 for POP3 and port 143 for IMAP (natch you must be allowed to access your webserver via HTTP...).
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