Question: What port is used?
Answer: Batch Services uses TCP port 25 to establish a connection with the SMTP host.
Question: What identity is used to connect to the email server?
Answer: No account is used to establish connection, but mail is delivered to user@hostname
as selected from the Address Book.
Question: What security measures are in place to prevent abuse of this feature (namely SPAM)?
Answer: Security should be performed on the SMTP server side.