About the MAFF file format
Support for reading and writing MAFF archives was provided in the Mozilla Application Suite, Firefox, and SeaMonkey thanks to the Mozilla Archive Format add-on from 2004 to 2018. While the original add-on is no longer maintained, the file format specification is still available and can be referenced by third-party software to provide better interoperability.
MAFF files can be opened using any ZIP extraction utility, and most operating systems can recognize them natively after changing the file extension from .maff to .zip. The original Mozilla Archive Format add-on also provided a procedure to convert MAFF files to other file formats, see the archive for details.