How do I set up a email whitelist using only procmailrc to protect my kids from unwanted email?

Question

How do I set up a email whitelist using only procmailrc to protect my kids from unwanted email?

I currently us the OS parental controls, but that is only good for the computer it is enabled on.

I understand that as my kids grow up, they'll figure out work arounds to any technical parental restrictions imposed upon them, but I want to at least understand the options that I have until then.

Answer 1

procmail can filter by the From header, and there are many recipe examples.

# This one discards all mail sent from the address below.
:0
* ^From: idiot@somehost.com
/dev/null

But don't forget that procmail only works with locally delivered mail. It won't affect mailboxes accessed over IMAP or webmail.

Answer 2

The one I use to send messages from myself to my phone:

VERBOSE=off
LOGFILE=/dev/null

# if it comes from a specific address(es), send to my cell
# it's be just as easy to whitelist a domain by adding another `|domain.tld` section to the bracketed regex
:0
* ^From.*[main.email.domain.tld|other.email.domain.tld]
* ^To.*datente
! 0000000000@vtext.com

# push everything else to my normal user
:0 
* .
! mainuser