Perhaps you do not want to read your mail in an MUA. If you use your web browser often, it might make sense to read and send your mail via a web interface, such as the one used by Gmail, Hotmail, or Yahoo! Mail. Ubuntu provides Squirrelmail for just that purpose. Squirrelmail is written in PHP and supports IMAP and SMTP. It supports MIME attachments and an address book and folders for segregating email.
You must configure your web server to work with PHP 4. You can find detailed installation instructions in
/usr/share/doc/squirrelmail/INSTALL. After you configure Squirrelmail, point your web browser to the default install location, www.yourdomain.com/squirelmail/, to read and send email.