Mail sends from @me.com instead of @icloud.com

So on all of my devices, my email sends from @icloud.com, except I noticed that my MacBook Air sends from @me.com. I migrated to iCloud when the switch happened and have never had this issue.

The Mail settings wont let me change anything, and the dropdown menu when I'm composing a message doesn't have @iCloud.com for me to select. Anybody know what's going on? I'd really rather not have to log out of iCloud on my computer since I use iCloud Drive extensively.