Mail : Different colors MacOs, IOS

You're tagging your question with Mail Extensions.

Note that this tag is related to the macOS MailKit framework. Your question does not apply to this.

Please consider to remove this tag.

And in order to receive a useful response from the community, it's recommended to detail your question. The color codes you refer to, what are they? Did you set them, or did you measure them? And how, where in your code or storyboard? etc.