DKIM, PTR, SPF? Replacing your MTA with MSMTP (+PHP, +System, +Apache)

Fuck you fuckin spammer! Because of the arms race it started that getting those message some days ago:

Undelivered Mail Returned to Sender[2a00:1450:4013:c00::1a] said: 550-5.7.1 [2a01:488:66:1000:5bfa:7407:0:1] Our system has detected that this 550-5.7.1 message does not meet IPv6 sending guidelines regarding PTR records 550-5.7.1 and authentication. Please review 550-5.7.1 for more 550 5.7.1 information. m131si2394453wmb.65 - gsmtp (in reply to end of DATA command)

TL;DR MSMTP is a beyond edge of plate tip when I ran into the DKIM issue. Nothing what follows is really new or surprising.

You can have a look at the Google Support page and this helpfull Serverfault answer.

Well, it seems that its nowadays finally necessary, to have DKIM, SPF and other fancy stuff alive to just send emails from you goddamned own server. I run Ubuntu 14.04 with Plesk and found this and this easy going tutorials. Well, I made some bad experience with MTAs and the other parts of the mail chain. So I really guess it won’t be easy. And maybe it wouldn’t be the final step but an ongoing process of an never ending arms race.

So is there a plan B?

After a little bit of chat (well, mostly complaining) @MorrisJbk told me about msmtp. With this tiny little tool an external provider could be used as the system MTA. Its transparent and also PHP could use it. That’s it!

Here is what I did to ship it.

Installing Msmtp and inital configuration

I followed the Archlinux msmtp Guide

apt-get install msmtp

Create a separate Google Account. You probably don’t want to use your main private account when your server went to a zombie spammer robot.

Configure the new credentials in /etc/msmtp

# Defauls for all accounts
auth           on
tls            on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
logfile        /var/log/mail.msmtp.log

# Gmail
account        gmail
port           587
user           your.mailer
password       [secret but plain!]

# Set a default account
account default : gmail

It’s also possible to use GPG instead of the plain password. Have a look at the Guide for that.

Next: Activate “Allow access from less secure apps” in Google’s Security Settings.

Add this to your /etc/mail.rc to have a transparent sendmail integration for CLI.

set sendmail=/usr/bin/msmtp

Now you can try sending a test email via command line:

mail -s "test subject" your@email.tld <<< "test message"

Enable MSMTP for PHP

I found this tutorial which describes it in detail.

First duplicate the msmtp config with Apache access right

cp /etc/msmtp /etc/msmtp_php
chown www-data:www-data /etc/msmtp_php
chmod 600 /etc/msmtp_php

Then start a separate logfile with appropriate Apache rights.

touch /var/log/mail.msmtp_php.log
chown www-data:www-data /var/log/mail.msmtp_php.log

Then activate it in php.ini:

sendmail_path = "/usr/bin/msmtp -C /etc/msmtp_php --logfile /var/log/mail.msmtp_php.log -a gmail -t"

Finally restart your Apache.

Voilá! There u go!

Why I write this post? First because I can. Second because I hate people who make other people more work than necessary!