Apple’s system status has been updated to note that a reported service issue with iCloud Mail does indeed reflect a known issue.
Beginning just before 12:00 PM PST, Apple noted that an issue with response time within iCloud Mail had impacted some users. The language offered by Apple doesn’t seem to suggest that it is a wide range of users begins affected just yet, but as the issue extends into the day, it’s likely that more users will experience the issue.
Here’s the report from Apple:
Apple says that if you are experiencing issues with any service, to contact support for any help that you may need. You can also use the source link below to stay on top of the service status, to see when the issue is reported fixed on their end.