"The delivery of some messages is being delayed and attachments may fail to download," Google said on its Gmail status dashboard.

"Between 0554 and 1530 Pacific Time today, 29.1% of messages received by Gmail users were delayed. The average (median) delay was just 2.6 seconds, but some mail was more severely delayed. However, this issue did not affect users' access to the Gmail page or other functionality."

At the time of writing Google said Gmail had been restored, writing that "The problem with Gmail should be resolved. We apologize for the inconvenience and thank you for your patience and continued support. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better."

Google was last affected by a major outage back in August, where a five minute outage caused global Internet traffic to fall by 40%.