Hi @n.thiel, 

Welcome to the Community! Sorry to hear you haven’t been seeing the results post-warming that you intended, would love to help! 

Did you complete the whole two weeks of warming process before starting to send those campaigns to your entire newsletter? Additionally, how frequently did you start sending those campaigns? While it might be exciting to initially see those high open rates during the warming process, it’s best to still slowly add more recipients to your campaign and slowly build up your frequency as a sudden increase could be the reason to these poorly performing campaigns. 

For instance, in our documentation , we recommend going progressively growing and sending to a 30 day → 60 day → 90 day engaged segments and so on in the warming process.

I suggest checking out these similar topics and concerns shared about the process and speed of warming as they have a lot of helpful resources and insights! 

Thanks for sharing your question with us and for participating in the Community!

-Taylor 

I hope these article helps 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://help.klaviyo.com/hc/en-us/articles/360025945671-Guide-to-Warming-Your-Sending-Infrastructure&ved=2ahUKEwiI3cbtmMH3AhXIzzgGHY9xBDkQFnoECAcQAQ&usg=AOvVaw0GbFVnbDU9sGF3nLyywHS0