Mailboxes provide a list of messages with short information about each. Mailbox messages appear on a separate panel in the frontend.
Home Assistant currently supports only the Asterisk Voicemail mailbox.
Each mailbox also provides an entity to indicate the number of messages available on the main page.
Building block integration
The mailbox integration cannot be directly used. You cannot create your own mailbox entities using this integration. This integration is a building block for other integrations to use, enabling them to create mailbox entities for you.