Kmail

From Grokdoc

KMail is a fully-featured email client that fits nicely into the K Desktop Environment, KDE. It has features such as support for IMAP, POP3, multiple accounts, powerful filters, PGP/GnuPG privacy, inline attachments, and much more.

It is quite easy and intuitive to use, but needs some previous configuration (like other email-reading programmes) which require a certain degree of technical knowledge which might be out of reach for newbies. Once configured, it is very powerfull, enabling users to read and write emails with a few mouse clicks.

The built-in PGP/GnuPG plugins, however don't work very well as far as signing goes (it includes the signature in the actual text instead of as an attachment), but this shouldn't be an issue as far as newbies are concerned. A detailed description on configuring KMail to use external OpenPGP plugins which include signatures as attachments can be found here.

When used with SpamAssassin it is very easy to have a spam free inbox. There are several walk throughs on configuring kmail filters to work with the spamassassin headers.

* http://www.tomchance.org.uk/research/random/kmail

One great feature is the attachment reminder function that whenever you write an email that contains certain keywords (like attachment or attached) and don't add an attachment to the mail, asks whether you forgot to add an attachment. Of course this funtionality can be turned off and customized (if you always write "see zip file" you can tell KMail to check for that phrase).

Another nice feature of kmail as is that it can easily read normal mbox type mail files there is no need to do an import unlike some other graphical mail clients.