For example. My domain is www.myuniquedomain.com. I see people sending email as me and Im getting the returned mail. Is there any way to stop this. I dont have relaying enabled. Basically using sendmail, one can send email as anyone. So i can setup an email server and send an email out as bill.gates@microsoft.com?

2nd question. Is there any code to disallow attachments to certain users. For example I have a user called webmaster@mydomain.com. He should never be getting an attachment whether it contain a virus or not. Is there a way to deny the email if there is an attachment?

I have done ample research on both of these topics. Just cannot find a solid solution.

Thanks in advance.

To keep people from sending e-mail as you using your sendmail smtp server - Look into SMTP Authentication - Meaning you must send a username & password to send the mail through sendmail - Kinda the same idea as POP3 when receiving e-mail.

I've never tried SMTP authentication, but I'm sure there is good documentation on it.