psGmail is a small trayicon application that allows you to check your Gmail account e-mail from a normal POP mail client (such as outlook, Thunderbird etc). Unlike standard email accounts which allow users to retrieve their e-mail through a POP mail client, Google's Gmail can only be checked on the web now. With psGmail, you can use your favorite POP mail client to retrieve your e-mail from your Gmail account. In addition, psGmail allows you to send e-mails through Gmail's service, as if it was a normal SMTP (outgoing mail) server.and it also can send you a msn-style alerts Instantly when you have a new email on Gmail.

Features of psGmail :
1. POP3/SMTP service base on Gmail of Google
2. Instant Email Alerts with msn-style(support multiple Gmail accounts)
3. fetch special email with filter function
4. fetch the emails in special label(eg: all mail)
5. http(s) proxy support, you can use it behind of firewall
and more options...
for details: http://www.vspire.com