In that case, forget about the logs, I doubt either company will show you the log files for the e-mail server.
The headers that you posted, was that from an e-mail you sent to yourself? I am trying to get a handle on the route the message took, and making some guesses what is happening at each step....
207.6.50.156 >
www.cancart.net @ 21:22:20 GMT
(The sender sends the message to his/her ISP)
www.cancart.net >
www.cancart.net @ 21:22:20 GMT
(The sender's ISP passes the message through their network)
www.cancart.net >
www.gdcdev.com @ 21:22:21 GMT
(The sender's ISP sends the message to your host)
www.gdcdev.com > priv-edmwaa11.telusplanet.net @ 23:49:16 GMT
(TWO HOURS LATER your ISP(?) gets the message, addressed to your real e-mail address)
priv-edmwaa11.telusplanet.net > priv-edmwes50.telusplanet.net @ 23:49:17 GMT
(Your ISP passes the message to your local mailserver)
So a few questions, assuming you sent this e-mail to yourself....
Was the e-mail written in a web based webmail type interface or did you send it from the web server or your own computer?
What is your domain name?
Is cancart.net your ISP or hosting company?
What about telusplanet.net?