SMTPMail question

[Guest]

Hello,
Please forgive this basic question. When sending mail using the SMTPMail
class in System.Web.Mail, how does the mail server know you are allowed to
send mail through it? For example, I used smtp.comcast.net as the Smpt Server
(because that is my internet provider), and it sent the mail fine. How does
this work since you don't supply a username or password? Does it know the
mail is coming from an ip address that has comcast service? I would
appreciate it if someone could explain it to me.
Thanks,
Rob

 

[CT]

The SMTP protocol doesn't authenticate you based on user name and password.
Instead it can reject relaying based on IP addresses and machine names.

 

[Guest]

Thank you!