Hi my name is Lefteris and i’m using an addon and i want to add a fix. I send an e-mail to the developer long time ago but no answer at all. i have already review the code and added the proper fix, i tested it and works fine. I send it to him but no answer. is there anything i can do? is there a way to publish a fix for the addon? or maybe to make a new addon with the same code? The addon is Released under Mozilla Public License, version 2.0. Thanks in advance!
If I understand it correctly you can release under a new name.
I suggest a similar name so it comes up when they search for the other extension and of course give credit, source link and explain as you did here why you released it and what the fix do.
Q6: I want to distribute software which is available under the MPL, either changed or unchanged, within my organization. What do I have to do?
Nothing. The right to private modification and distribution (and inside a company or organization counts as ‘private’) is another right guaranteed by free and open source software licenses, including the MPL.
Ok i’ll try that and what happens! 
Thanks for your answer!