Mailbox is required for setting up Help Scout integration to create a conversation used for call logging.
Note - If no mailbox id is entered, by default a random mailbox will be chosen by the system based on the response from Help Scout's API.

To find mailbox id use the following steps -
- Choose the mailbox from the availble list

2. Click on the setting button and select “Edit Mailbox”

3. copy the mailbox id present in url