There is the possibility to assign a category to a mail, and as a result the mail gets a coloured rectangle:
Is it possible to colour the whole message, like this?
Thanks
Unfortunately, changing the background color is not possible in Outlook natively. The closest you can get is changing the font properties, such as the family, color or formatting (bold, italics, etc.) And as far as colors go, you are limited to a basic 16 colors.
If you decide that this could work for you, this is how you would go about doing it:
I typically use these rules to change the font color of mail entries where I am in the "To:" field or the "Cc:" field, or mails from me that I receive (such as sending to a distribution list of which I am a member). There's a lot of support for different conditions, but unfortunately, you can only alter the font and not the background.
I hope this helps.