Add Switchboard notifications section to the handbook

- Incidents in non-impacting lifecycle stages won't appear

- If incident occurs during maintenance, both incident and maintenance statuses will be displayed

### Checking for Past Notifications in Switchboard

Switchboard allows for the [Communications Lead](/handbook/engineering/infrastructure-platforms/incident-management/roles/communications-lead/) to create outbound communications (see [Sending Notifications Using Switchboard](dedicated_cmoc/#sending-notifications-using-switchboard)). When troubleshooting Dedicated support tickets, checking if any Notifications have been sent can be a helpful first step.

All customer notifications are logged in Switchboard. To view past notifications:

1. Click on your profile in the top left corner

2. Select `Customer notifications`

3. Click on the Title of the relevant notification to view the message and its recipients

Watch this [overview on YouTube](https://www.youtube.com/watch?v=e2ZRD8csjow) of how these notifications are created and how they can be viewed in Switchboard.

- **Visibility of what the email looks like from a customer's perspective**

  The following is an example of a notification about an incident. It is from the test environment but formatting will be the same.

  ![Example email screenshot](/images/support/switchboard_comms_email_example.png)

- **Sender's email address**

  The sender's email address will depend on the Switchboard environment. Here are the two email addresses used for customer tenants:

  - Production: `switchboard@gitlab-dedicated.com`

  - Preprod: `switchboard@gitlab-dedicated.systems`

- **Email subject(s) used**

  - Investigating alerts on your GitLab Dedicated instance

  - Update: Investigating your GitLab Dedicated instance

  - Update: High-priority response for your GitLab Dedicated instance

  - Update: Working to resolve your GitLab Dedicated instance issue

  - Resolved: Your GitLab Dedicated instance is operational

  - Emergency maintenance scheduled for your GitLab Dedicated instance

  - Emergency maintenance completed

  These can also be found in the [templates](https://gitlab.com/gitlab-com/gl-infra/gitlab-dedicated/switchboard/-/tree/main/lib/tenants/notification_templates) and new ones may be added over time.

- **Possible backend checks to confirm if an email has been delivered to the customer's mail servers**

  This will not be available. Switchboard can confirm that an email was sent and you can access historical notifications using Switchboard but we cannot confirm whether an email was successfully delivered to the customer's mail server. We can only confirm that it was sent.

### Version information

Check the `Tenant Details` collapsible section.