Why are my automated confirmation / subscription emails getting flagged as spam in gmail?

Question

So I have a rails app set up with devise that sends out account confirmation and password reset emails. The emails get sent out using the sendmail command using postfix for smtp. I have DKIM set up and gmail is accepting the signatures as valid. I also have SPF set up correctly.

Gmail is giving me this message as an "explanation" of why my emails are getting spammed:

Why is this message in Spam? It contains content that's typically used in spam messages.

As descriptive as that is, I have no idea what content in particular is typically used in spam messages. I've tried tweaking the text, changing to html, then to text+html, changing the from address, adding the user's full name to the to address in addition to the email. I'm stumped. Maybe another pair of eyeballs can point out something stupid that I've simply overlooked.

The full text of the message follows with personally identifiable information redacted.

Delivered-To: myaddress@gmail.com
Received: by 10.216.199.130 with SMTP id x2csp42610wen;
        Sun, 16 Jun 2013 13:16:13 -0700 (PDT)
X-Received: by 10.224.174.6 with SMTP id r6mr13525400qaz.87.1371413772413;
        Sun, 16 Jun 2013 13:16:12 -0700 (PDT)
Return-Path: <account-services@booyango.com>
Received: from booyango.com (node1.booyango.com. [97.107.138.232])
        by mx.google.com with ESMTP id k6si3223197qcj.4.2013.06.16.13.16.11
        for <myaddress@gmail.com>;
        Sun, 16 Jun 2013 13:16:12 -0700 (PDT)
Received-SPF: pass (google.com: domain of account-services@booyango.com designates 97.107.138.232 as permitted sender) client-ip=97.107.138.232;
Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of account-services@booyango.com designates 97.107.138.232 as permitted sender) smtp.mail=account-services@booyango.com;
       dkim=pass header.i=@booyango.com
Received: by booyango.com (Postfix, from userid 33)
    id 7CEC133DF5; Sun, 16 Jun 2013 20:16:11 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=booyango.com;
    s=default; t=1371413771;
    bh=iXfBZB6q0fPI+Yms0E8FC1P/T9J+3enBFtTrsjcTADY=;
    h=Date:From:Reply-To:To:Subject;
    b=AGw4SXj6UN0lpEo0FSO91s3aAYDsmAHZVqBvvYGQPW6Jp1UhfAQFlIE1AYY0CcoUq
     Xb3Mn4vul1WXpdWIZMPEgHXJ3SwvEvSxDfDEeYTNiGRoI+DW7vFopTo+1rQeLLdS/B
     j6iIKFsJUAOz0n1yh9/gasXJeOv4fmK6+ZoMhLfQ=
Date: Sun, 16 Jun 2013 20:16:11 +0000
From: Booyango Account Services <account-services@booyango.com>
Reply-To: Booyango Account Services <account-services@booyango.com>
To: me <myaddress@gmail.com>
Message-ID: <51be1d0b55c16_44f38e887057054@node1.booyango.com.mail>
Subject: [Booyango] Reset password instructions
Mime-Version: 1.0
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: 7bit

Oops, it looks like you lost your Booyango password.

You can use the following link within the next 24 hours to reset your password:

http://booyango.com/users/password/edit?reset_password_token=<reset_token>

Thanks,
The Booyango Team

Answer 1

I have had problems with this in the past, and found solutions to be largely hit and miss. If the server which is sending your mail happens to be on a black list because of previous spammers linked to your server/IP address, you are probably out of luck. Otherwise, I have had limited success by playing with different header variables; also plain text emails tend to have higher delivery success rates than HTML - in my experience (although, I realise you are already doing this).

Also try rephrasing your subject line or body text, you may just be getting caught by a spam rule looking out for a pattern you have accidently stumbled upon.

Answer 2

I found the my devise or rails emails were sent to gmail span if

1) they included a link (ex. confirmation token)

2) the subject was blank