This plugin by Marcel Bokhorst enables the sending and receiving of e-mail messages on the administration panel and optionally receive SMS messages containing the sender, subject and (part of) the text when new messages arrive.
All e-mail is text based (HTML will be converted to text). However, it is possible to view HTML messages and to download attachments. Mail can be received by POP3 or IMAP and sent by PHP mail or SMTP. Attaching files is possible. There is a simple address book for both e-mail addresses and phone numbers, which can optionally be populated with your WordPress users.
This plugin requires at least PHP 5.2.4.
Plugin homepage: http://blog.bokhorst.biz/2414/computers-en-internet/wordpress-plugin-mini-mail-dashboard-widget/
