Retain format / style of text pasted into Gmail composition

While coding, there are cases one will want to keep important code snippets into a private repository using Gmail. That's what I wanted to do, and what I actually did. Or one may want to send it to their friends to help them.

I prefer keeping the original formatting of the IDE to losing them while pasting. Unfortunately, simple copy from the IDE and paste into Gmail sometimes worked but not always. Google search gave results mostly about how to remove annoying formatting instead of how to retain them, quite frustrating.

There is one option one to check:

If the 'plain text mode' is checked in the mail composition window (unchecked in the above image), then you will see the contents pasted there only. Formatting is all gone.