Recently we started to have issues with GMail deliverability. They go straight to spam folder ("Why is this message in spam? It is similar to messages that were identified as spam in the past" or "Why is this message in Spam? It’s similar to messages that were detected by our spam filters.").

At the very beginning - we do not send spam. All our subscribers wanted to get our messages and opted in. We send only updates about new courses for doctors (subject: '[course name] - [our company name] invites to participate.' or similar). We do not send e-mails with promotions or deals ('XYZ is 20% off today only').

As great majority of our database are people who already participated in one of our courses I would say this should be classified as 'update'. Especially that doctors have to attend to this kind of events to maintain their medical license. I seriously doubt that our emails were marked as spam by many people (and Gmail somehow proves it by not displaying "Be careful with this message. Many people marked similar messages as spam.")

Some tech informations:

  • emailing software is PHPlist
  • emails are delivered via Amazon SES
  • volume is less than 10.000 emails at a time
  • speed is throttled to ~3000 mails/hr
  • unsubscribe link is available
  • messages are in HTML
  • messages do not include embedded images
  • messages do not include attachments
  • subject doesn't contain spammy words
  • messages are signed with DKIM, SPF and DMARC records are in place
  • abuse@domainname inbox is created
  • bounces are monitored
  • Amazon dashboard states bounce rate of 0.07%
  • Amazon dashboard states complaint rate of 0,00%
  • another providers we checked are accepting our emails, often in main inbox
  • Spam Assassin doesn't think it is spam
  • mail-tester.com gives result 9.9/10
  • we are not blacklisted according to MXtoolbox on any blacklist
  • messages include our company physical address
  • sending volume is rather equal over the year
  • we have never had problem with sending spam (ex. infected Outlook client)
  • Google Postmaster tools shows no delivery problems (0.0%), no spam reports (0.0%), no encryption or authentication problems
  • Google Postmaster tools think our sending domain has "low reputation" and it doesn't change over a time (I ask why...)

So, everything seems to be ok (beside low domain reputation). Anyway, Gmail thinks we send spam. The problem started ~2 month ago without any obvious reason. For us it is a big issue as ~50% of our users use Gmail. Before problems we had 1300-1500 unique views on average and 200-300 unique clicks (of total ~9000 subscribers). Now... well, it is 600-700 unique views and 70-100 unique clicks. We can clearly see a drop in our web page visits. I reviewed clicks and I can see that Gmail visitors are single cases - probably people who have our address in their contact list.

What I already tried:

  1. changing PHPlist domain
  2. throttle speed even more
  3. including personalized informations in mail content ('Hello, John Smith')
  4. contacting with Google via bulk sender form (no answer of course)
  5. changing server (different ip) and PHPlist domain
  6. changing list owner email address
  7. changing unsubscribe links
  8. changing email layout
  9. not including our company address
  10. embedding photos instead of using img src=""/
  11. sending through main company address ([email protected]), another mail ([email protected]) and different domain ([email protected]).

Important parts of Gmail headers:

ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816;

ARC-Authentication-Results: i=1; mx.google.com;
       dkim=pass (...)
header.s=chxstv4ywotb74ucsaa3265lc3w5tk3g header.b=TTBoWTLD;
       dkim=pass (...)
header.s=uku4taia5b5tsbglxyj6zym32efj7xqv header.b=sbLFFGou;
       spf=pass (...)
       dmarc=pass (...)

Return-Path: <-ses id here->@eu-west-1.amazonses.com>

Authentication-Results: mx.google.com;
       dkim=pass (...)
       dkim=pass (...)
       spf=pass (...)
       dmarc=pass (...)

X-Mailer: PHPMailer 5.2.22 (https://github.com/PHPMailer/PHPMailer)
X-phpList-version: 3.3.6
X-MessageID: 48
X-ListMember: <recipient's address here>
Precedence: bulk
List-Help: <my link here>
List-Unsubscribe: <my link here>
List-Subscribe: <my link here>
List-Owner: <mailto:<admin address here>>
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="b1_6097fb563f9b3e23a1adb69a15d9a857"
X-SES-Outgoing: 2019.01.24-
Feedback-ID: 1.eu-west-1.S5UHOeTqBrb6Ryr7oI5SxxxxDucKmZWIcZskfAPIebw=:AmazonSES

According to GMail we are sending spam. Period. I have no idea how GMail identifies it since I tried to change absolutely every variable I have found.

I have also found out that when we test newly created Gmail account we are spam, but after 10-20 emails we start to be a promotion / update / main inbox on this particular account (without marking it as not spam)

I am out of ideas. I suspect that there is some major issue but I cannot find it. The only idea I have left is to directly ask our customers to take out our messages from spam and put them into updates - really, great for our image and so professional... What else can I do? What have I overlooked?

Thank you!

  • Where you able to solve this? How?
    – Imageree
    Apr 18, 2019 at 19:35
  • 1
    @Imageree no, nothing has changed. Domain reputation is bad and nothing we've tried helped.
    – pp_1
    Apr 19, 2019 at 7:16
  • I'm also getting killed by this. Just in the last month. I'm not even a bulk emailer, I'm just a small business (lawyer); I used to be a software/IT guy so I've always set up my own servers. This particular one has been fine for four years, with SPF and DKIM set up (just set up DMARC now, but that shouldn't be a dealbreaker). With some recipients it repeatedly flags my emails -- i.e., they report one email as not spam, and G Suite still flags future messages as spam. MXtoolbox reports all ok. I'm losing potential clients because they email me, I reply, and it goes to spam. No clear cause. May 23, 2019 at 16:42
  • You don't mention RDNS/PTR -- make sure you have that set, in both IPv4 and IPv6. I had it set in IPv4 but not IPv6, which I just fixed. Not sure if that was it for me, but seems plausible. May 25, 2019 at 4:52
  • IPv6 PTR did not work, at least overnight, but forcing my mail server to send over IPv4 (i.e., turning off IPv6 in postfix) did work. Probably related to the IPv6 address reputation, or maybe the PTR takes more time to propagate. For now, just sending over IPv4 works for me. May 25, 2019 at 17:05

2 Answers 2


You should post your message on the Amazon SES forum because the issue comes from Amazon SES IPs being blacklisted not you!

Check your post above and you will see that the Amazon IP your email was sent from is still blacklisted on ZapBL for example: https://mxtoolbox.com/SuperTool.aspx?action=blacklist%3a54.240.7.12&run=toolpage

  • This is what did the trick for us, not the SPF which had no effect. We had to switch to another region. What the hell, gmail??
    – Toolkit
    Mar 15, 2023 at 8:17

After long time I have found the problem.

And the problem is... Gmail.

Gmail was incorrectly parsing the SPF record. The record itself was correct and it was validating correctly in ie. mxtoolbox. It was also validating correctly in Gmail (yeah, look at the listings in first post about validation results).

However, checking it with Google's MX checker https://toolbox.googleapps.com/apps/checkmx/ was giving 'unable to parse' error. I modified it. The correct outcome of MX check should be:

SPF must allow Google servers to send mail on behalf of your domain.

providing you don't use GSuite.

After this change deliverability instantly increased, and after some time domain reputation also went up.

  • How did you modify it? I am using the SPF record v=spf1 a include:_spf.google.com include:spf.phplist.com ~all and I also get a parse error in google's mx checker: No valid SPF record for included domain: spf.phplist.com: include:spf.phplist.com
    – gnebehay
    Sep 12, 2020 at 12:33
  • @gnebehay I don't use phplist.com, only their software installed on my server. According to their manual your SPF is correct: phplist.com/knowledgebase/dmarc-spf-and-dkim-settings so I'd contact their support.
    – pp_1
    Sep 14, 2020 at 8:10
  • had no effects for us. We switched to other region from EUWest1
    – Toolkit
    Mar 15, 2023 at 8:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.