The second iCloud outage in a week left 15 million users unable to access iCloud mail on Monday.

Apple confirmed that iCloud was experiencing problems in a status update issued Monday, which said that 12 per cent of customers were effected by an outage that left users unable to access iCloud mail.

Users were left frustrated without answers during iCloud’s downtime, as Apple waited until after the service was back up and running before posting the status update on its website.

This is the second time in a week that Apple’s iCloud has experienced problems. On Friday, we reported that some users were unable to access their online mail inbox for several hours.

At its Q2 financial earnings conference call in April, Apple announced that iCloud had reached 125 million users in just six months.

Apple plans to retire MobileMe at the end of June, but earlier this month Apple began informing MobileMe customers who hadn’t yet transitioned to iCloud that they could continue using their or email addresses and calendar after the 30 June deadline passes.