1000 FAQs, 500 tutorials and explanatory videos. Here, there are only solutions!
Colouring or differentiating the emails received in the Webmail
An alternative solution could be to set up a sorting filter, enabling you to sort your emails by sender (learn more).
Example: creating an Oliver folder and then creating a sorting rule with the following condition "If the sender is Oliver" and the following action "Move as unread message to the Oliver folder". You will thus have a view of the Webmail letting you know when a specific folder fills up with its displaying the number of unread messages.
Link to this FAQ: