Preventing Recipients from getting an email. - How Email Processing Works?

Question

When you send an email with this:

From: Jeff@yahoo.com
To: XXX@aol.com, XXX@aol.com, XXX@aol.com
CC: james@gmail.com

Which Mail Server sends the message via email to the recipients in the TO & CC field? Is it the SMTP server or the server owned by the recipient (like aol.com)?

Answer 1

When you write an email and send it, you will hand it off to some SMTP server you have access to. That server will then contact the recipients server (or intermediate server) and deliver the email to that SMTP server. The SMTP server on the receiving end will somehow, depending on their setup, deliver the email to their users.

In your example, you will properly give yahoo.com's SMTP server the email. Then that server will contact aol.com and deliver the email there. It will also contact gmail.com and deliver the email to their SMTP server.

You should read this part of the SMTP rfc which have a very good explanation about the process.

How you will go about preventing that an email is delivered, is to somehow control one of the SMTP servers that is contacted in the process - or not send the email at all. When you see the email delivered in your own mailbox, it is properly way to late trying to prevent the other recipients receiving the email.