At about 3:25pm yesterday (Monday 23rd September 2013), Google Apps suffered some service issues. Clients were noticing issues sending or receiving emails.
Google estimated that this issue affected less than 0.024% of the GMail user base.
Their team provided updates constantly every hour and at 7PM they confirmed the issue was much more widespread than first thought, affecting 50% of GMail users.
At 3AM this morning (24th September), Google confirmed that the issue was resolved and provided this statement:
As of 1600 Pacific Time, Gmail message delivery and attachment download is functioning normally for all users. We apologize for the duration of today’s event; we’re aware that prompt email delivery is an important part of the Gmail experience, and today’s experience fell far short of our standards. We have analyzed the data on user impact and are providing a preliminary assessment of what occurred:
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.