Ryan, we had the same issue with Apple (@mac.com, @me.com, @icloud.com) emails. Same, did nothing out of the ordinary. 

Hi ​@ryan-salesflow and ​@MattyO, 

Higher than normal bounces from Apple inboxes did occur. At around 10:00 am ET, 11/18 these bounces became more frequent and Klaviyo was alerted to the issue.

Through mitigation and escalation through channels our team was able to work with Apple and the issue was resolved by 6:00 ET as their intention was not to block this traffic in the first place.

Our team will continue to work with Apple to make sure an oversight like this does not happen again.

As a next step, you would be able to clone these campaigns and send to anyone who may have bounced from an Apple inbox (Typically mac.com, icloud.com, and me.com). Our status page will always give you up-to-date information if any issue does arise. 

~Chloe