Hello! Thank you very much for responding. I have a couple quick questions concerning business letters. When including an e-mail address and/or website address within the body of the letter is there a rule on formatting? Is the address underlined or perhaps highlighted in a different color than standard black? Do the same rules apply to the body of the letter as well as in the signature? Thank you for your help!
The format of email addresses and website addresses is enough to indicate what they are. There is no need to highlight them unless you want to.
I would definitely NOT underline becuase that would make any underscores ( _ ) in the address very difficult to read.

Our company style is to place them in italics, but that's just our house style. As mentioned above, there is no rule for this.

If you create the letter in Word, DO remove the hyperlink that it will create automatically or it will look like a link, and not like text.