i made a form to upload fonts on server and i put validation rule only accept file with .ttf and .otf extension and its working with .ttf format but when i upload .otf extension file format the validation fails.
So it seems that the mime types for web-fonts are not really finished yet and they are still changing. I've read about changing the family to font/ttf and so on.
However otf stands for open font type. You can try the following mime type instead for that