I'm been trying to understand why Gmail is treating the email sent from one of my domain/server as SPAM. I found a lot of threads here about this issue, however I checked the usual suspects like domain keys, spf etc.

My email is accepted by Outlook.com, which from my understanding has a lot more aggressive spam filter.

I tested my config using auth-results@verifier.port25.com and I got this:

SPF check:          pass
DomainKeys check:   neutral
DKIM check:         pass
Sender-ID check:    pass
SpamAssassin check: ham

Everything looks fine.

After sending an email to a gmail account I get this under the headers:

Received-SPF: pass (google.com: domain of user@mydomain.org designates 89.x.x.8 as permitted sender) client-ip=89.x.x.x;
Authentication-Results: mx.google.com;
       spf=pass (google.com: domain of user@mydomain.org designates 89.x.x.8 as permitted sender) smtp.mail=user@mydomain.org;
       dkim=pass header.i=@mydomain.org

As you can see, the email is passing on spf and dkim without issues on gmail servers.

Finally I checked my server IP, hostname and domain at http://mxtoolbox.com/blacklists.aspx for RBL blocks and they're not listed anywhere.

Why is gmail treating my emails as SPAM? It makes no sense, I've complied with every single good practice.

Other Note:

  • Reverse DNS is also ok;
  • Tests at http://www.allaboutspam.com are green except for Email server is not using BATV format;

Thank you.

  • TCB13 - I know this might be too obvious, but what is the content of the emails you're sending like? Have you run them through spam checks? – Dave Holland Jun 18 '14 at 15:57
  • What is the message that Gmail displayed at the top of the message, describing why it was marked as spam? – Michael Hampton Jun 18 '14 at 16:01
  • @MichaelHampton "Why is this message in Spam? It's similar to messages that were detected by our spam filters. Learn more" and they send me to this link support.google.com/mail/answer/…. – TCB13 Jun 18 '14 at 16:14
  • @DaveHolland I've tried multiple contents, HTML and plain text, all result on the same issue. The last one was "This is another email test, please ignore." – TCB13 Jun 18 '14 at 16:15
  • TCB13 - Most of the time it comes down to content... unless your specific domain has had a lot of spam complaints in the past. Is this a new domain that you're just starting to mail from, or no? – Dave Holland Jun 19 '14 at 17:39

Apparently after a few days it start working fine.

Right now, I guess what really matters in GMAIL is actually passing this tests:

SPF check:          pass
DomainKeys check:   neutral
DKIM check:         pass
Sender-ID check:    pass
SpamAssassin check: ham

And wait 3 or 4 days so google can update their servers. Seems like the spam filter does some kind of internal cache on DKIM and SPF lookups for a particular domain.

UPDATE: This problem seems to be back, I've no ideia how to fix it.

  • 1
    Unless you send a lot of e-mail from your server, slowly ramp up the sending from it, and get a lot of people to mark it as "not spam", then you will always hit this issue. This has to do with the magical black box that Google/Microsoft use to filter e-mail. There's more about it here: penguindreams.org/blog/… – djsumdog Oct 2 '18 at 21:27

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