Hi, Evon. I'm Robinson, and I’m happy to help you today.
Adobe Flash Player reached the end of life on December 31, 2020 and since January 12, 2021 Adobe started to block the Flash content from running in Flash Player, this is why you are seeing this error.
Unfortunately, since Adobe started to block Flash content from running in Flash Player there is nothing that you can do to fix this, you will need to use another email client.
You can see this information in the link below.
https://www.adobe.com/products/flashplayer/end-...
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
A good alternative to Incredimail is the new Outlook app, which is a free email client. You can see more information in the link below.
https://support.microsoft.com/en-us/office/gett...
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.