Calypso is a free email client that doesn't skimp on features, and can handle multiple email accounts that are either POP3 or IMAP.

It's simple to use, looking pretty much like any other email client and making use of wizards to guide you through the adding/editing email accounts process.

Much of the interface can be adapted to suit your tastes, including adding or removing buttons from the toolbar.

Mailboxes are automatically backed up at regular intervals, so there's no need to worry about losing any data.

HTML email can be viewed as text, which is a great function for when companies only offer HTML emails.

A handy feature is Blind Send which allows you to send an email to multiple individuals, but ensures that each individual believes they are the only recipient.

Auto-response is also possible, with a different message for each account. Only one auto-response will be sent to an email address, regardless of how many emails you receive from them.

Other neat features include mailing list support, and password protection so that your inbox cannot be viewed by unauthorised persons.