EmailTray 

EmailTray is an application for monitoring, displaying, and prioritizing multiple e-mail accounts. It supports both POP and IMAP protocols, and also most popular web-based e-mail services like Gmail, Windows Live, Hotmail, Yahoo!, and AOL Mail. EmailTray analyzes all the e-mails received from selected accounts and assigns a priority rank to each e-mail. This is based upon user's interaction with the mail sender. There are three priority ranks: Top Priority, Low Priority, and No Priority.

An e-mail is classified as top priority if the user frequently exchanges e-mails with the sender. The number of e-mails received from the sender doesn't matter, they will get a higher priority only if the user replies to them, or reads them frequently. The other two ranks are assigned in a similar manner. Priorities can be also manually modified.

After you install the program, it will display a small icon in the Windows taskbar and notify you of each mail received. Depending on the priority rank, there are customizable sounds and alerts for each e-mail type. A useful option is that it can check spam folders from each account, to retrieve any important mail that got there by mistake.

E-mails can be accessed from an interface very similar to Microsoft Outlook. If an e-mail is deleted from EmailTray, it will be also deleted from its inbox. This synchronization works only one way, deleting a received e-mail from Yahoo! Inbox, for example, will not delete it from EmailTray as well.

Overall, it is a useful application for users with a lot of e-mail accounts that need constant monitoring.