Any way to color label your emails in Mac Mail like you can files?

Yes, using mail rules. Go to prefs -> rules -> add new and select the criteria and in action, select set colour.

Thanks! I didn’t know about that.

How about on the fly, for instance similar to “flagging” it.

If your mail rules are set up based on sender for example, it will be applied to any incoming message from that sender….....which is kind of on the fly, but you would need to do some set-up.
Alternatively select the message, go to Format and Show Colours to select the one you want to apply.

Mail Act-On is a little Mail.app plugin that lets you define rules that you can invoke on the currently selected message(s) with very simple keystrokes. It’s easy to set up, and I’ve used it for a long time to color and move messages manually.

I’m not sure if u can just apply colors like by right clicking like in finder but u can create rules that highlight anything that maches the criteria in a chosen color b

@sumul has the only solution I have found to tag messages with a color label (or other Mail rules) on the fly.

Select the email(s), Press Shift + ⌘ + C, select a colour. Done! :)