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Brian Armstrong
Asked: 2009-08-11 10:50:10 +0800 CST

Postfix with DKIM on Ubuntu

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I want to improve deliverability for my outgoing emails with DKIM. I've gotten dkim-filter installed for postfix, using this tutorial https://help.ubuntu.com/community/Postfix/DKIM

It seems to be working, my /var/log/mail.log shows it starting:

Aug 10 18:34:13 mail dkim-filter[5284]: Sendmail DKIM Filter v2.8.2 starting (args: -x /etc/dkim-filter.conf -u dkim-filter -P /var/run/dkim-filter/dkim-filter.pid -p inet:8891@localhost)

However, no headers are being generated when I send email and I can't figure out why.

Here is my /etc/dkim-filter.conf https://gist.github.com/6dc92c7efc29aa45991f

And here's what I added to the bottom of /etc/postfix/main.cf

# DKIM
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891
non_smtpd_milters = inet:localhost:8891

Any ideas? Thank you!

P.S. I have the DNS entry setup for it as well at feedmailpro.com (may still be propagating), but I assume it isn't even being checked without the headers in outgoing emails. Thanks!

ubuntu postfix domain dkim

2 Answers

  1. Best Answer

    Ok I figured out why. It was because I was sending email with a from address different than my domain. Once I changed the from address to an address to [email protected], it started signing them.

    This is obvious in hindsight since i guess that's what domain keys do, is sign the from domain. For some reason I had assumed it was signing based on the return path or the mail server IP, and not the from address.

    Since I'm building an ESP (email service provider) I need the ability to send email from lots of domains. So my next challenge is to get it signing for all domains.

    Edit: Solution posted here DKIM sign outgoing mail from any domain (with Postfix and Ubuntu)

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  2. I've got a postfix install with DKIM signature on multiple domains. I've found that it was easier to configure amavisd-new to do that signature than using dkim-filter. Anyway, I would have added amavisd-new to my email stack in order to do spam checking.

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