Unix command 'mail', send mail to an .onion address mail

Question

In my server, I installed tor and postfix. I can send an email via this simple shell commands :

echo "foo" | mail -s "example" [email protected] 

No problem here, its work.

Now, I want be able to send emails to .onion address. So When I execute this command :

echo "foo" | mail -s "example" [email protected]

The mail isn't received in my email address. Below my mail.log logs :

Nov 29 00:50:10 mycomputername postfix/pickup[6641]: 49B4F342961: uid=1001 from=myunixuser

Nov 29 00:50:10 mycomputername postfix/cleanup[6974]: 49B4F342961: message-id=<20161128235010.49B4F342961@mycomputername>

Nov 29 00:50:10 mycomputername postfix/qmgr[6642]: 49B4F342961: from=, size=297, nrcpt=1 (queue active)

Nov 29 00:50:10 mycomputername postfix/smtp[6976]: 49B4F342961: to=, relay=none, delay=0.19, delays=0.12/0.01/0.05/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for name=sigaintevyh2rzvw.onion type=AAAA: Host not found)

I think I must configure my 'mail' command for use the proxy tor, but I don't know how I can do that and I didn't find any doc/tutorial.. Thank you =)

Answer 1

Short answer, mail uses Unix sockets, and you cannot Torify it.

Longer answer:

AFAIK mail uses the sendmail API via socks to send mail to the local mail daemon/mail forwarder of the Unix machine.

So at the end of the day, you want to make that postfix Tor aware, or use something else to send emails that talks TCP.

I have never done that, found a related article here: SMTP over Hidden Services with postfix

The setup proposed for sending and receiving email in this article is interesting for who is familiar with postfix.

Basically, it is torifying /usr/lib/postfix/smtp, the email transport daemon component.

It proposes then several solutions for for the ones who want to receive email, in which one of them proposes a configuration where non-authenticated email is received in port localhost:25, and tor is configure to talk with localhost:2525, where only authenticated users will have emails forwarded. The 3rd one seems to be more interesting, I have yet to think about it later on.