eFax

eFax is an internet fax software owned by J2 Global^[1]. J2 Global was founded in 1995 as JFAX.com. eFax Messenger is software which can send and receive image files in the proprietary .EFX file format.^[2]

File Identification

J2 Global's original JFAX service used a file format based on the TIFF-F format with a .JFX extension. Also known as J2 Messenger^[3].

Version 3 & 4 of the .EFX file format is proprietary and begins with hex values DCFE then 2 bytes of unknown values then 6 bytes 00000000FFFF.

Version 5 is unknown.

Screenshots

Software

• Current Version of eFax Messenger
• Archived version of eFax v3 (Mac) & v4 (Windows)

References

1. ↑ https://en.wikipedia.org/wiki/J2_Global
2. ↑ https://www.efax.com/efax-help-center/efax-messenger/viewing-faxes
3. ↑ https://www.jconnect.com/supported-file-types