how do you disable Mail on Macbook air

Re: "how do you disable Mail on Macbook air"

You can remove email accounts, if any.

See how to: Remove or temporarily turn off email accounts in Mail on Mac - Apple Support

Seems Mail is one of the built-in apps that MacOS requires, so the app itself can not be removed.

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Re: "I use gmail from within Chrome on Mac book Air.

However, Mail continuously pops up saying it can’t send messages. Very distracting."

If you haven't already (as it would seem): you can simply change the default email app:

See how to: Change the default web browser or email app on Mac - Apple Support

You appear to have a stuck message pending send.

As suggested above, delete the email accounts.

Mail app cannot be deleted.