Marked as Spam high for Yahoo and Hotmail

  • 20 March 2023
  • 5 replies

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I am in the process of cleaning up our list, and while I have managed to improve openrate, clickrate, and revenue per subscriber, we are suffering from a high marked as spam rate.

However, these are coming from Yahoo and Hotmail accounts.

In the past 90 days, we have had 89 out of 49,139 emails marked as spam. However, of those 89, 61 are from Yahoo and Hotmail, who received 15,100 emails. That means around 30% of emails received 69% of our spam complaints.

Could there be a reason for this? I would blame it on single opt-in, but the rate is going up, not down, after turning double opt-in on.

I could also blame it on increased sending rate. However, I wrote a series of emails telling the subscribers how often I would send to them, so it is a predictable twice a week on average.

So, considering these spam complaints are coming from Yahoo and Hotmail over other emails by a huge amount, what could the problem be?

As an aside, gmail has the highest unsubscribe rate. I’m not fussed by a higher unsubscribe rate, as the product is for nail fungus, and once the user is cured, they’re not going to want to get our emails anymore, whether or not they bought our product.


Best answer by inboxingmaestro 21 March 2023, 19:55

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Hello @Stom 

While I can understand how frustrating deliverability issues could be, it’s important to understand why emails are going into the spam folder. What’s contributing more to emails landing into spam - content, list quality, frequency, or authentication issues?

Even after implementing double optin, your spam complaints are high, then it’s highly likely your content relevancy and frequency is not matching to your subscriber expectations. I’m not sure about the content you are sending, your list building methods, list composition (Gmail vs. Yahoo vs. Outlook) or any association with affiliate marketing practices recently or in the past or your business as a whole.

But, it’d be a good starting point if you follow a deliverability troubleshooting checklist recommended by Klaviyo here -

Also, I’d advise to monitor the Gmail Postmaster & Outlook SNDS report (if you’re a dedicated IP sender), to see your domain & IP reputation health.

Just FYI - Yahoo spam filters look for specific signals in emails such as a blacklisted IP, poor domain reputation, user complaints. If it finds any of these signals in emails, it’ll put them into recipients’ spam folders. As for Outlook (Microsoft), it’s a tricky one and challenging. However, following email best practices and ensuring better engagement and sending practices will help to improve deliverability.

Let me know if you have any questions.

P.S: Get your email programs audited by a deliverability consultant who can help you see what’s causing the issue across all ISPs and how to fix that. I’d be happy to talk further if you’d like to fix your deliverability issues. Check out @inboxingmaestro for more details.



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I am taking every step to try and make our content relevant and useful, and not just promotion spam. I would go first toward content and making sure we were bulletproof, but considering the split between email providers, I thought there might be something else.


I’m talking “marked as spam”, though. I mean, users specifically marking as spam. I thought that adding double opt in would help here, but it hasn’t. And the spam rare for gmail is fine. It’s literally just crazy high rates for Yahoo and Hotmail. And that’s what I’m not understanding.


I’m interested in if anyone else has seen this? If there’s anything that I can change to specifically impact marked as spam rates for yahoo and hotmail, or if this is just a freak thing.

Userlevel 5
Badge +18

Thanks for the response. Couple of followup questions -

  1. What do you mean by, ‘split between email providers’? Are you using multiple ESPs and audience is overlap among multiple ESPs?
  2. What’s your sending frequency to Yahoo & Outlook audience?
  3. When have you started seeing spikes in the spam complaints for Yahoo & Outlook? Have you changed anything in your sending practices?
  4. Have you gone through the warmup & ramp up for reputation build up?
  5. Can you send a test email (your last campaign that you’ve sent) to my test ids: , ,



P.S: Like I’ve said it earlier, an audit would be a first step to identify what’s happening with yoru email programs and be really helpful to fix your deliverability issues. Happy to connect and talk further.

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Thank you.

I took over the list at the end of January. I segmented down to 30 day engaged, etc., then realized I had some deliverability issues with gmail, so excluded them and started to send to very highly engaged, highly engaged, etc., for gmail.

I am sending to the list 2 times a week, Tuesday and Thursday. Once a month we have a campaign, most recently for St. Patrick’s Day, where there will be emails sent on other days.

I am getting poor openrates for 60 day+ engaged segments. They decreased quickly and considerably, I feel because nearly all of the potential contacts entered the 30 day engaged segment. Openrates for 30 day segment are 50-60%.

Openrate for the last 90 day segment I sent to was 6.3%. I have not sent outside 30 day since.

Marked as spam rates are across all segments, but as seen in the screenshot, it’s very much skewed toward yahoo and hotmail.

Thank you for the help, I’m just traveling, so I will send you a test email of today’s campaign as soon as I’m home.

Userlevel 5
Badge +18

Thanks for sharing this, Tom! Please respond to my above few questions that are unanswered that’ll help connect the dots basis whatever limited information that you have shared, if that makes sense.

Nevertheless, it looks like deliverability issues across all the top tier ISPs - Gmail, Yahoo & Outlook domains, since you had some issues at Gmail in the past. 

Also, as you have mentioned, that you had single opt-in method of list building and now you have moved to COI list building method, it looks like SOI opt-in data is very probably the culprit here for increased spam complaints and deliverability issues. May be you also need to look at your subscription practices and identify if signups are actually real signups (and not bots).

  • Have you been removing or excluding folks who are complaining from your list?
  • What about unsubscribe rates across Gmail, Yahoo & Outlook?
  • How is the unsubscribe process work currently - one click or hard to follow?
  • Are spam complaints high for broadcast email campaigns or flows? What flows are live currently?
  • Can you share the website domain and email sending domain?
  • What Gmail Postmaster is telling you about your email reputation, users reporting spam?

Couple of thoughts from my end:

  1. Check if your authentication records are properly setup, passed and domains are aligned in the header.
  2. Segment and target your core engaged audience (open/click in the last 30 days) only (ISP wise) for couple of weeks until you see consistent positive engagement across ISPs and reduced spam complaints.
  3. Run your unengaged/dormant/lesser engaged audience through an email validation system to remove any bad email ids.
  4. Maintain a regular sending cadence to your core audience and avoid targeting your unengaged or lesser engaged audience until spam complaints and deliverability issues are solved.
  5. Revisit your email content strategy for the core audience and test different content style to improve open rates and click-to-open rates.
  6. Capture email content and frequency preference using a subscription center to understand your audience better and deliver relevant personalised content.
  7. Increase your triggered email programs (flows) to boost up your email performance and build trust with ISPs like Gmail, Yahoo & Outlook that you are sending wanted & relevant emails.
  8. Last but not the least, check if your unsubscribe process is easy to follow (one click is recommended) and working.