Noojee Fax

Features
T.30 (fax over PSTN) and T.38 (fax over IP) support
Use your existing email client to send and receive faxes
Send MS-Word documents as a fax and a large variety of other file types
Provide a private fax line for every staff member and have faxes delivered directly to their email inbox
Send a fax to multiple recipients just by adding additional 'To' addresses.
Automatic delivery receipts delivered to your email inbox
Received faxes can be delivered as either a tiff or pdf attachment or an inline tiff.
Archives inbound and outbound faxes in a central location
Simple to install
Built as an extension to Asterisk
Support all Asterisk compatible hardware (including Digium)
Also able to work with most Fax modems directly under Linux without needing Asterisk
Send multiple attachments in one single fax transmission.
Email body can be used as a coversheet to attachments.
Supports a large number of file formats including: Tiff, Postscript, PDF, Microsoft Word, OpenOffice Writer and others.
Can be integrated into other business applications via SMTP or SOAP interface.
Preview faxes before they are sent.