I am using Php 8.0 and I am not using the SpartPost mailer. I am using the custom Mail Server provided by my hosting provider and I haven’t touched the PHP settings for a while now. I already reinstalled the plugin but it didn’t resolve the issue. The only thing I did in the last couple of weeks was experimenting with Cache Plugins. I have W3 Cache installed but even when i deactivate all the newly added plugins i get the same Error.