On Tuesday, Google offered more details about the cause of the problem and the steps it's taking to prevent it from happening again.
The cause was a "very rare" dual network failure, which brought down two separate, redundant network paths, according to a blog post from Sabrina Farmer, senior site reliability engineering manager for Gmail.
"The two network failures were unrelated, but in combination they reduced Gmails capacity to deliver messages to users," she wrote.
Over the next few weeks, Google staffers will work on bulking up network and backup capacity for Gmail, as well as on making Gmail's message delivery more resilient in the event of a network crash, according to Farmer.
"Finally, were updating our internal practices so that we can more quickly and effectively respond to network issues," she wrote.
Juan Carlos Perez covers enterprise communication/collaboration suites, operating systems, browsers and general technology breaking news for The IDG News Service. Follow Juan on Twitter at @JuanCPerezIDG.