Downloaded all files from old iMac on external hard drive. Plugged hard drive to new MacMini . After I downloaded all the apps, I saw Thunderbird app down in the dock. I clicked to lunch the app and got a window that said Thunderbird was damaged and to move it to the trash. I am running Thunderbird on another device, but this new computer will be primary, I would rater stay with Thunderbird and not use Mail. Csn you help me or tell me in steps what to do. I can get my emails on my iPhone. Thank you. James