how to protect the emails from your domain, to be used as FROM fields

Question

we have severals domains, with their corresponding servers hosted on linux (ubuntu).

sendmail lets you send emails, allowing for changing of the envelope. Here a simple example - which works with no extra settings:

sendmail -f bill.gates@microsoft.com -t destination@example.com

is there a way to stop others from using any email adresses registered with our domains?

thanks.

Answer 1

is there a way to stop others from using any email adresses registered with our domains?

You can't stop them, but you can make it more difficult (i.e. increase the chance it will be caught and marked as spam).

This is what SPF has been designed for (from Wikipedia):

Sender Policy Framework (SPF) is an email validation system designed to prevent email spam by detecting email spoofing, a common vulnerability, by verifying sender IP addresses. SPF allows administrators to specify which hosts are allowed to send mail from a given domain by creating a specific SPF record (or TXT record) in the Domain Name System (DNS).