Tracing Original Source

[LEnglish]

Hello.
Can anyone tell me if I can find out if there is a third party involved in an email I have received or if I can find out if the email was written by some one else? I often receive emails from a person whom I know is not writing them. Is there a way to find out if they came from another source?
Thanks so much, LE

[Chrispcritters]

Do you mean that you think multiple people are using the same email address?

[LEnglish]

Hi. No I mean that Im trying to find out if there is someone replying on behalf of some one, which is then forwarded or copied and pasted into a new email from the person it is supposed to come from.