Cirrus CI itself doesn't have built-in mechanism to send notifications but, since Cirrus CI is following best practices of integrating with GitHub, it's possible to configure a GitHub action that will send any kind of notifications.

Here is a full list of curated Cirrus Actions for GitHub including ones to send notifications: cirrus-actions.

Email Action

Email GitHub Action allows to send email notifications on Cirrus CI Checks completion. Simply add the following to you .github/main.workflow workflow file:

action "Cirrus CI Email" {
  uses = "docker://cirrusactions/email:latest"
  env = {
    APP_NAME = "Cirrus CI"

Check full documentation here.