Firefox is not an email client, and it has nothing to do with your Verizon account. When you click on a mailto: link, the browser selects a program to open it based on perhaps what it can find when it is installed, but also what you set it to. I gave instructions for doing that [[https://support.mozilla.org/en-US/questions/1024658|here]]. Whatever you were using for mail, (e.g. Outlook) can be started without starting a browser. There is an outside chance that M$ has unintentionally or intentionally made Outlook not work as a result of no longer making IE your default browser. More likely, Firefox is now opening a different email program that works differently. You can open IE again, and find out what email program it was using by starting it. Help | About is a common place to find out what it is. Close it all out, and follow the instructions at the link above to set the email program. There is also a possibility that something has gone wrong with the mail storage files(s)/folder(s) on your computer, in which case you may need to 1) reinstall the mail program, 2) get an expert to fiddle with it, e.g. by setting permissions, 3) format your HD and reinstall windows. Although it is rare, saved emails can be stored on a server; in which case you will need to contact Verizon to help fix the problem. In this case, it seems very unlikely to be Mozilla's fault. Warning: one time I uninstalled IE, only to find I needed it later for web development. Win7 absolutely refused to reinstall it later, and I had to reformat and reinstall windows in order to get it to work again. Uninstalling IE is a step you probably don't want to take, unless you are sure you never want to use it until you reinstall it or get a new computer.