MathQuill for Gmail for Chrome
More About MathQuill for Gmail
using a graphical formula editor.
The script uses MathQuill as the formula editor, and the CodeCogs
server (with their generous permission ) for generating the images.
When editing a mail, press Ctrl-M to insert a formula. Edit the
formula that appears in the interactive formula editor. Press enter to
convert it into a picture. (You have to exit the formula editor via
enter, otherwise the picture will not be updated.)
To edit an existing formula, either click on it, or position the cursor after it and press Ctrl-M.
See the Wiki (https://github.com/dominique-unruh/mathquill-for-gmail/wiki) for more information.
 Please note that if you are generating a lot of equations from a
single domain, i.e. over 3000/day, then you may need to arrange a
commercial licence with CodeCogs to support continued hosting of the
service. Please see their terms and conditions: