Can someone try this and tell me if you see it? 

$ torsocks telnet tmg3kli67jlbcduh.onion 25

I can see it and send myself email using postfix.
My hidden service mail server won't be up all the time for now, but I'll put up a dedicated computer for it later.

Send mail through torsocks by modifying the master.cf.

Instructions:

Step 1.
In /usr/local/etc/tor/torrc
uncomment the lines 

HiddenServiceDir /usr/local/var/lib/tor/
HiddenServicePort 25 127.0.0.1:25

Restart tor

Step 2.
Then go get the domain name in /usr/local/var/lib/tor/hostname and write it down.

Step 3.
Then change the postfix domain to the hidden service domain in /etc/postfix/main.cf, as well as changing your host name to include your new hidden service domain name.
 
Step 4.
Replace smtp with smtp_tor and make the file smtp_tor executable in the directory /usr/lib/postfix/

Create /usr/lib/postfix/smtp_tor with the following content: 
#!/bin/sh 
torsocks /usr/lib/postfix/smtp $@

Step 5.
Then modify /etc/postfix/master.cf

smtp      unix  -  - n - 1 smtp
relay     unix  -  - n - - smtp 

to be 

smtp      unix  -  - n - 1 smtp_tor
relay     unix  -  - n - - smtp_tor 


Step 6. Setup an account and login/password for your anonymous name, postmap it in /etc/postfix/virtual, then reload and restart postfix.

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Then when you're able to, send me a test email using TLS.

 >>/233/

I think this is how I'm going to email anonymously, if it works. Hidden service + TLS 1.2 + pgp RSA:4096, self hosted.  Set it up and try it out.