Forwarding email to myself to change a sent date

Hi,

Can someone edit messages in a chain of emails to make it look as if a message was sent when it wasn't?

I've received a chain of emails that have been sent back and forth from myself to someone else. Within this chain is a message that I can't find I ever received, but the other party has forwarded the chain in which this message is included.

A friend of mine has suggested that the other party my have forwarded the email to himself, added the message, sent it back to himself, and finally forwarded it to me, after deleting the final part of the email which shows where he forwarded to himself.

Does this make sense, and how can I check?

Any advice would be appreciated.

Thanks,

Nat