AnswerGFI FaxMaker Online client supports both protocols HTTPS or SMTP to send faxes. The support for HTTPS has been integrated with the latest available GFI FaxMaker Online build (starting with build 05 June 2014.)
The difference between HTTPS and SMTP is the method how the fax request is submitted by GFI FaxMaker Online client. With HTTPS protocol the GFI FaxMaker Online client makes secure HTTPS API calls using port 443 while with SMTP protocol the GFI FaxMaker Online client submits fax requests as emails using port 25 to send faxes.
When HTTPS submission method is used, GFI FaxMaker Online client will not generate notification reports. For SMTP submission method the sender will receive a send transmission report, if notifications are configured.