You can easily setup imap for Gmail app, when you want to receive Gmail through any separate email client like outlook. You need to activate Gmail IMAP Settings so that the email client knows how to retrieve your Gmail messages. Here listed some steps to activate imap in Gmail: - 

Firstly, open Gmail in a web browser

Click on Settings in the right corner

Click on "See all Settings"

Then click on "Forwarding and POP/IMAP tab.

Now, in the imap access. click on "Enable POP"

Click on "Save".

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