I’m going to link all the already opened topics about this feature request. The earliest dating about 7 years ago.
https://forum.emclient.com/emclient/topics/_mark_read_on_new_email_notification_feature_request
https://forum.emclient.com/t/mark-read-on-new-email-notification-feature-request
I can only put two links in a post, but the first link actually have the rest of the links
Hopefully this makes a clear point that is a pretty popular feature request. Which it’s already implemented in other mail clients such as Outlook.