According Apple's website, iCloud: Mail & Notes is currently experiencing performance issues, with less than 1% of users being affected by this problem. Considering that iCloud has over 150 million users, we can estimate that over 1 million people could be affected and you could be among them. If in the following hours you will not be able to access your iCloud.com email address, then you should know that the problem comes from Apple's servers and not from you. It is not known when the problem will be solved, but in the next few hours everything should return to normal.
