How to check the origin of mail?

Question

I want to encode a small service where I can send an email to a specific address used by my server to send specific commands to my server.

I will check the list of allowed email addresses to make sure that none of the unauthorized ones sends the command to the server, but how can I make sure that, say, the email sent by "mrzombie @ thezombie.net" really comes from "thezombie.net"?

I thought about checking the header of the source IP email server and checking the domain to make sure it is the same, but will it be reliable?

Example:

The server receives a command from [e-mail] [e-mail] is allowed, proceed to check The server checks the IP address of thezombie.net from the header: WXYZ Server pings "thezombie.net" for it IP: ABCD IP addresses do not match, do not process the team

Is there a better way to do this?

Answer 1

If you can solve this problem for general emails, you have solved the SPAM problem.

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Answer 2

, , , , "[e-mail]" "thezombie.net"?

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Answer 3

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Authenticating content with a digital signature is the best way.