iCloud 
Save a draft email
In iCloud Mail, email messages are saved automatically as you’re working on them.
Save an email message as a draft
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As you work on messages, they’re saved automatically as drafts.
Each time a message is saved, the new draft overwrites the previous one.
Open a draft email message
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Select the Drafts folder in the sidebar, then double-click the message.
When you send the message, the draft version is removed from the Drafts folder.
You can save space in your iCloud Mail mailbox by deleting draft messages you don’t plan to send.