Searching through this forum I see multiple requests to fix a problem with sometimes being unable to scroll down the message window when viewing an email. Sometimes opening a different email it will scroll ok and then returning to the original email it won’t scroll down. This is frustrating. If you left click the top header portion of the email and wait about 3 seconds, the email will then scroll down ok. There seems to be no rational explanation as to which emails will scroll and which wont. I am on the latest software 7.2.37929.0 but this problem has been reported on the forum for about the last 5 years or so and I can’t find anybody posting a solution. Interestingly, my wife and I both run EM Client for email on HP laptops with Windows 10. Her machine has the problem and mine doesn’t. The laptops are not identical.
You could try uninstall eM Client, making sure NOT to delete the database directory when prompted, then download and install it again from the Release History.