Please follow The Steps below. On the left-hand side you will see the different catagories. In the window on the right you will now see the options associated with Identity.
Most people use their full name.
You only need to worry about Reply-to address , Organization , or Signature File if those apply to you. If you don't know what those are used for, then just leave them blank. Next, look back on the left and click on Mail Server Capitalization is very important in this section. Make sure everything is all lowercase letters. You don't need to worry about any of the other selections in the lower section.