Apple appears to have quietly tripled the number of iCloud Mail aliases users can create, increasing the limit from three to nine. The increase was first noticed last week by a Reddit user, and picked up shortly after by a member of the Mac Rumors forums. Mac Rumors can confirm the change is live at iCloud.com.
The increased limit has not been mentioned by Apple, so it could conceivably be a test, but that seems unlikely. It's a nice perk to have, but as of this writing, Apple's iCloud User Guide still says the maximum number of aliases allowed is three.
Source: MacRumors · Summarized by HeadlinesBriefing