We currently use banners with different colors to display different types of message.
Blue for Info message
Green for Success message
Red for Error message
Orange for Warning message
Problem, colorblind people hardly distinguish some colors from some others. As a result, they can't get the immediate clue of the importance of a message, and a Warning message can be overlooked, or a Success message might look like a scary warning before they read it and realize it's ok.
Here are two simulations of different types of colorblindness for non-visually impaired people to realize how similar they look:
Add icons to reinforce the message types. The icons should be universally recognized and provide immediate info at a glance.
Here's how non-colorblind people would see it:
Here's how colorblind people would see it.
Additionally, those icons can provide more info on their meaning on hover to make sure it's easy to learn and understand.