This is not really a question directly about Firefox.

Presumably you are using webmail, and so editing and writing emails on Firefox. For details check with your webmail's support or help.

• see also http://simple.wikipedia.org/wiki/Webmail

The usual procedure is to simply edit the list of names and addresses. Possibly each address will have a clickable cross to delete it.if you want a more specific answer please say who is your webmail with ?

(Only the part after the @ is needed not your full address)

This depends on a couple of things:

(1) Desktop version of Firefox

In most cases, you will need to manually edit the forward header inserted into the message after you click Forward but before you click Send.

You can test by sending it to yourself.

If that isn't working, can you mention what site are you using, for example Yahoo, Gmail, Outlook.com?

(2) Firefox OS device

I'm not personally familiar with the mail app.

(3) Other -- please give more detail on how you are composing your forward.