Which IP will the receiver see in the email?

[PowerUp]

Assume I connect online from Japan. I host a domain and the host is based in USA. I logon to the webmail of this domain. I send an email to somebody in UK. Will the person receiving that email in UK see that the email is sent from a Japan IP or US IP?

Thanks.

[g1smd]

Often both appear in webmail headers: the IP of the server, and the IP of the person using that server.

[phranque]

it depends on how the webmail script is programmed.
for example, i am looking at an email received from a "contact us" form i set up.
this is not essentially different from webmail functionality.
other than the email headers i specifically added, the mail server added headers that identify the host and mail servers by domain name and the mail server by ip address.
within the body of the email i have included the ip address of the "web user", so the information is certainly available to the webmail script in your case.
you can easily test this by sending yourself a webmail and examining the body and headers.