For almost 12 hours on Monday, Google's Gmail service suffered from delivery delays and a backlog of messages due to the failure of two unrelated network paths.
The outage began at 5.54am PST, and the backlog of messages was cleared by 4.00pm PST, Google said in a blog post. The company said that 71 percent of messages had no delay, and that the average delay on the 29 percent of affected messages was 2.6 seconds.
Significant delays of more than two hours did occur for 1.5 percent of messages, and Google said that "users who attempted to download large attachments on affected messages encountered errors".
The company said that although the failure of two separate, redundant network paths is a rare event, it is looking to improve network capacity and make message delivery more resilient to a loss in network capacity.
"We're updating our internal practices so that we can more quickly and effectively respond to network issues," wrote Sabrina Farmer, senior site reliability engineering manager for Gmail.
"We'll be working on all of these improvements and more over the next few weeks — even including this event, Gmail remains well above 99.9 percent available, and we intend to keep it that way!"