Sudden decline in open rates - trying to determine cause

  • 2 March 2022
  • 3 replies

Badge +2

We market to consumers and physicians. We have both consumer and physician emails in our Klaviyo profile but we use different sender emails / reply to emails for consumers vs. physicians.

Up until recently we have very high open rates for our consumer emails (50%+) … recently they have significantly declined over a 6 week period, I haven’t changed any of the content. The only thing I can think of is a slow down during the holiday break as our target consumer is very busy during that time.  


The only thing I can think of is that we sent a few emails starting in December to a small (less than 500 recipients but about 5 campaigns total) group of physicians who we met a while back at a tradeshow. We imported the list and we had never sent to them before. We had high bounce rates with this campaign, although open rates have been high and consistent. I think the bounce rates come from many physicians having strict spam filters and some of the emails were old. 


Do you think the bounce rate increase from this new physician campaign is impacting my deliverability on other emails? Also would it make a difference that I use different sender email / reply to emails for each customer group? 


Best answer by David To 3 March 2022, 22:04

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Userlevel 7
Badge +60

Hello @Erin225,

Welcome to the Klaviyo Community!

If you haven’t already, I would suggest taking a look at the How to Troubleshoot Decreasing KPIs Help Center article that covers improving a number of these key indicator such as open and click rate. It’s important to note that inbox providers will take note of senders who have a high bounce rate which will have a negative impact on your deliverability performance, and thus, on your sender reputation. 

Typically speaking, using different sender emails or reply to emails wouldn’t impact deliverability unless you are using a sender/from address whose domain is not consistent or does not match your brand. By ensuring your sending address includes your domain name, it indicates to inbox providers that you are a legitimate sender with a legitimate business. For example, if my brand name is Dave’s Apparels, I’ll want my sender addresses to sending from,, etc. 

Since it also sounds like you took a brief break during the holiday season from your sending, I would advise following along to our warming guide. With any plans to increase sending throughputs, we highly suggest going through a warming process to slow increase the audience size you are looking to expand to. This also applies to resuming to normal sending capacity after a decrease or pause in sending. Major fluctuations in sending practices is also noticed by inbox providers and can come off as suspicious when a sending suddenly begins sending large volumes of emails. 

I would also advise taking a look at some of the additional resources we offer which I’ve included below. There’s also a number of Community posts on this topic that I think may prove helpful to review as well!



I hope this helps!


Badge +2

Thanks David … a quick follow up questions.

We own two different domains - one is for Canada and the other is US. Both domains / websites have our brand name but are slightly different. We do all our email for both countries through Klaviyo, but we do change the sender email slightly between the two countries. In your example above, could these two sender emails cause a negative impact on deliverability? 

Userlevel 7
Badge +60

Hey @Erin225,

That could certainly cause a negative impact on your deliverability!

Since each Klaviyo account can only utilize one sending domain, it’s recommended that if you own multiple domains/websites, each one should be connected to their own dedicated Klaviyo account. For example, if I owned two websites/domains (Canada) and (US), I would also want to have two separate Klaviyo accounts each utilizing their own sending domain. Something like within the Canadian site/domain linked Klaviyo account and for the US site/domain linked one. 

@ashley_mcdermott also offers a great course titled Running a Multinational Business that goes over some of these basics in operating multiple international stores alongside Klaviyo.