If they operate their own SMTP server they can put anything they want in the
headers OE shows you.

"Eric" wrote in message
...
Thank you very much for your suggestions
If anyone can put anybody else's email address in the sender email address
field without authorization required, can they receive anybody else's
email
address?

Furthermore, if the domain name for email address uses dynamic IP Address,
which is not allowed to send into any hotmail account based on their
policy.
Can anyone put anybody's else email address, which domain name uses a
static
IP Address, and send into any hotmail account. Even through anyone is
using a
dynamic IP Address, but from the viewpoint of hotmail server, which can
see a
static IP Address, and skipping the hotmail policy.
I look forward to your reply

"N. Miller" wrote:

On Wed, 7 May 2008 07:28:08 -0700, Eric wrote:

For example, , @abc.com is my domain name, receiving
email
uses POP3, and sending email uses SMTP, can any unknown sender send any
out-going email under without getting any authority from
the
source abc.com? If they can successfully send out email, do they access
my
SMTP illegally?
Thanks in advance for any suggestions

Anybody can put anybody else's email address in the sender email address
field. No authorization required (except in rare cases, where the service
provide requires verification of the sender email address). They normally
can't access any SMTP message submission server without access
permissions
granted by the server administrator; unless the server is intentionally
configured as an open relay.