You can add, remove, and edit your Keeping mailbox from the Keeping settings page. You'll need to be admin in order to do this.
Go to the Keeping settings page for mailboxes.
Click the "Add Mailbox" button on the upper left.
Choose a name for the Mailbox, and enter in the email address for the Gmail address connected to this mailbox. This is often something like support@ or help@. You can also choose which agents will get access to this mailbox, and then click Add Mailbox to continue.
Back on the main page for this mailbox, copy the unique Keeping email address for this mailbox. You can click on the icon next to the address or highlight the text and use the copy function in your browser.
Activate your Keeping Mailbox by following the steps on how to forward your Gmail to Keeping.