As everybody knows, Debian Iceweasel and Icedove are deprecated, but we continue its maintenance.

• https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=815006
• https://glandium.org/blog/?p=3622
• http://fossforce.com/2017/02/great-debian-iceweasel-icedove-saga/

I thought it would be good to update their app icons as Mozilla did with Firefox Quantum and Thunderbird some time ago, and thought on these options:

• proposing this in the mailing list, and ask the community to create new designs
• taking icons from, for example, Antu icon theme (here are the icons for iceweasel and icedove)

The point of all of these is to give Iceweasel/Icedove a soft and modern icon design in harmony with their new UIs, even Tor Browser did this when it upgraded to Quantum