how to notice if a mail is a forwarded mail?

how to notice if a mail is a forwarded mail?

References

Reference NO 1

http://www.netmanners.com/382/5-rules-of-forwarding-email/

Reference NO 2

http://stackoverflow.com/questions/13646559/how-to-notice-if-a-mail-is-a-forwarded-mail

Reference NO 3

http://ask.metafilter.com/184956/Can-I-dectect-if-an-email-has-been-forwarded

Reference NO 4

http://en.wikipedia.org/wiki/Email_forwarding

Reference NO 5

http://digitalsurvival.blogspot.com/2011/03/find-out-if-someone-has-read-and-or.html

Reference NO 6

http://lifehacker.com/5981928/bananatag-tracks-your-outgoing-email-tells-you-which-messages-were-opened

Reference NO 7

http://alumni.unc.edu/article.aspx?sid=192

Reference NO 8

https://moversguide.usps.com/