Less secure appin Admin Console
Login in to your Admin Console and Go to [Security] -> [Access and data control] -> [Less secure apps].
Choose 'Allow users to manage their access to less secure apps' and save
Login to your Google Workspace email and go to
Forwarding and POP/IMAP tab. You can see
POP Download section.
Enable POP for all mail and save settings.
Login to your Gmail account and go to
Accounts and import tab. And click
Import mail and contacts link.
Enter your Google Workspace email in popup and click
Enter your Google Workspace email password. And input POP username and POP server information like bellow.
If you see
Could not validate this combination of email address and password error like below, you should use
App password to process.
Go to Google My Account page of your Google Workspace account. and Go to [Security] -> [App passwords] page.
You will get the
App password. You should use this password in previous popup. Input password and click
Check import options as you want. And click
Start import to start.