If an email client automatically forwards a message to another email address, and the email was not opened in the originally designated account, the original email will not count towards the email delivery statistics as having been opened or forwarded. For example, if an organization sends a message to a constituent's work email address, and that account is setup to automatically forward to the their personal email address, it will only show as having been opened if the email is opened in the personal email account. 

It will only count as one open, and it will not count as a forward since it is an auto-forward.