Google has revealed that a lack of disk space is what caused its fledgling social network, Google+, to spam users with multiple notification emails for each new event.

Some Google+ users were understandably disappointed when, on seeing a plethora of new friend add notifications and assuming that their hilarious answers to the mundane profile questions had gone viral, they discovered it was in fact one new friend update sent 26 times.

Appropriately, Google's head of social, Vic Gundotra, posted his heartfelt apology on Google+.

Sorry seems to be the hardest word

He wrote, "Please accept our apologies for the spam we caused this afternoon.

"For about 80 minutes we ran out of disk space on the service that keeps track of notifications. Hence our system continued to try sending notifications. Over and over again. Yikes.

"We didn't expect to hit these high thresholds so quickly, but we should have.

"Thank you for helping us during this field trial, and once again, we are very sorry for the spam."

From Google+ via TechEye