This is a tutorial on how to make other people see your tail, muzzle and wing on a server where Tails mod is not installed on.

Please note that only those people will see your tails who has Tails mod installed.

SO!

1: Install Forge 1.7.10 (yes, 1.7.10)
2: Install Tails mod (1.7.10 version, put it in the mods folder)
3: In the .minecraft folder, delete options.txt (Because 1.7.10 will pretty much crash when you load up a world or join a server with 1.10.2 options.)
4: Launch 1.7.10, it'll ask to download FoxLib. Click yes. (it'll download automatically)
5: Go on a singleplayer world, and set your tail, muzzle, ears, and wings. (Go to the Pause menu, click on the "Tails" button at the bottom, and set your stuffs. You can change between tail, muzzle, etc by clicking on the button in the upper left corner.)
6: Click on the Export button. Save it somewhere.
7: Go on minecraft.net, and upload your skin exported from Tails mod 1.7.10 (I hope I don't have to explain how to upload a skin..)
8: Launch up 1.10.2 Forge with Tails mod installed. Go on a server, and enjoy!

I figured it out and tried it out myself, it DOES actually work! ^^

I hope I helped! Have a great day! ^^