If you’re trying to check your Apple-supplied email you might be out of luck. Some users are currently unable to access iCloud services or even the iCloud site.
Apple’s services system status page shows that all services are working normally. Unfortunately, that’s going to help you check your email which is currently down for some (including myself).
We’re reaching out to Apple to see what the issue is and will update this article when we hear back.
UPDATE 4:24PM PT: Apple’s system status page now shows that all iCloud services “may be unavailable for some users.” The time section of the page shows that the issue started at around 3:15PM PT.
UPDATE: Looks like Apple has fixed iCloud services. According the system status page and my own ability to check my email again, everything is working again.