We have seen no recurrance of this issue, so we are setting the status to resolved. We apologise for any inconvenience caused.


This morning we experienced unexpected bursts of load across all systems that caused slow or failing connections for a period of time, with a sudden spike at 11:00 UTC. Engineers investigating the issue enabled DoS protections that have reduced the impact and all services have returned to normal levels. Email servers should retry delivery as per the RFC standard if required. We will continue to monitor traffic levels and we apologise for any inconvenience caused. Email protection and filtering was not affected.


Engineers are investigating inbound connection issues across the Email Security service. This is unexpected and is being treated as a critical issue. Further updates will be provided as soon as we have them

Began at:

Affected components
  • Email Security
    • Europe