InterFAX is an online fax service, allowing you to fax from any application using SMTP email messages. Sending a fax programmatically through the InterFAX fax SMTP interface is as simple as generating a regular email message. InterFAX also provides an advanced fax API with multiple destinations, deferred transmission, document resolution, and more.
Fax SMTP Samples, Documentation and Discussion Forum
The Samples section shows examples of parameters that are passed under different SMTP faxing scenarios.
The Reference section defines all available parameters.
The Developer Forum allows you to discuss fax SMTP interface issues with other developers and with InterFAX staff.