Hi ​@Stuart – thanks for posting and pleased to see you’re keeping your list healthy and seeing great results from it! I have also had occasional weeks where there’s an unusually large uptick in opens and it’s always a funny feeling of not quite believing that that’s real. Have you taken a look at unique opens and unique clicks and compared those to from before you cleaned your list? My guess is if your open rates went from 45-55% to 65-70% it’s just because when you cleaned the list you removed that 10% of recipients who did not regularly open. Sorry I don’t have better advice but I hope your very high open rates continue on!

When you recently did your list cleaning I suspect you might have cleaned out a lot of people not showing Apple Opens. Which would mean the people left on your list as a % are more apple openers than in the past. 

One thing you might want to look at is to go to the Metrics page.

Select “Opened Email” and set the filter to “Apple Privacy Open” = true and then also =false. This will give you a better sense of if you are actually getting more opens during the time period your curious about. 

Here’s a link as well to read more about iOS MPP Openers - https://help.klaviyo.com/hc/en-us/articles/4416791883163