We have identified the cause of the issues in the German datacentre, delaying some mail delivery for our European customers. This has been due to a sustained, substantial increase in mail delivery rates to the load balancers at this site, causing higher than expected load.
We have deployed additional resources to the affected systems, and monitoring is showing that messages delivery is starting to return to normal. There will be a catch-up period where mail may continue to experience short delays in delivery, whilst any accumulated message backlog is cleared.
We are continuing our expansion and enhancement of our infrastructure, to address these issues and prevent these from presenting in future.