To limit who can send email to your channel, go to the channel name, select More options > Get email address, and then select the advanced settings link.
From there, you can manage who's able to access the email address for that channel. You can restrict the audience to include only team members who own that channel, or narrow your audience to specific domains. You can also remove your current email address entirely.
Note: If your IT admin has disabled the ability to send email to channels, the Get email address option won't appear.
Go to the desktop or web app to manage who can send email to a channel.