When do you use the forward in an email?

normal forward means, someone send you a massage and you can send the exact massage to someone else, which also includes, all the recipients who got the mail so far.

Auto forwarding is, say u have 2 email accounts. then u just want to check 1 mail account, so on the other email, u do the auto forward , so your massage will be automatically forwarded to the 1st email account.