Some newsletters are experiencing incomplete post sends

This incident has been resolved.

Our email sending provider identified the root cause as a bad deploy on their end, which they reverted ~40 minutes ago. All posts are sending successfully, we will continue to monitor closely over the rest of the day.

We are continuing to work with the vendor for a comprehensive fix to the issue but have implemented a workaround and are delivering the dropped emails for all effected newsletter sends

We have identified an issue with an upstream email provider resulting in some posts not being delivered to the full intended subscriber list. It is effecting ~20% of large publications with an average impact of a 4-8% non delivered rate. We are working with the vendor to resolve the issue and will deliver all posts to impacted subscribers.