Every step below is from an official source
Switch from iCloud Mail to Gmail
What to do at iCloud Mail before you leave, what Gmail needs when you join, and everything else the switch touches. Your full plan is built in your browser and stays there.
Official sources reviewed . How we review sources
At iCloud Mail, before you leave
Forward iCloud Mail to your new addressBefore
At icloud.com/mail, open Settings, select Mail Forwarding, tick Forward my email to and enter the new address.
Automatically forward email in Mail on iCloud.comApple. ReviewedDecide whether to keep forwarded copiesDuring
Select Delete messages after forwarding if you don't want copies kept in iCloud. Keeping copies uses your iCloud storage.
Automatically forward email in Mail on iCloud.comApple. ReviewedExport your contacts as a vCardBefore
At icloud.com/contacts, select contacts, or use the Actions button to Select All Contacts. Then select the Share button and choose Export vCard. This needs a tablet or computer.
Import, export, or print contacts on iCloud.comApple. Reviewed
At Gmail, when you join
Import mail and contacts in Gmail settingsDuring
On a computer, open Gmail settings, go to the Accounts and import tab and click Import mail and contacts. Follow the steps on screen, then start the import.
Add another email account on your computer - Gmail HelpGoogle. ReviewedCheck what the import brings overBefore
Gmail imports messages but not folders or labels. Your other email account needs POP access.
Add another email account on your computer - Gmail HelpGoogle. ReviewedExpect 30 days of forwarding after importAfter
After you import, Gmail forwards messages sent to your other account for 30 days.
Add another email account on your computer - Gmail HelpGoogle. ReviewedPlan for the end of POP mail fetchingBefore
Gmail is ending POP fetching from other accounts. Existing users can use it until January 2027. Importing mail and contacts on the web still works, but it is a one-time import that does not keep syncing.
Then: everything else the switch affects
The steps above are what iCloud Mail and Gmail say. Your full checklist adds the accounts, codes, payments and devices that depend on your email provider, in a safe order. It's built from your answers, in your browser.