Please describe your feature request:

Even if the shoutrrr library does support this configuration, it's not possible to easily configure it with notify.

Currently, we are using an ugly hack by injecting this parameter into the subject variable:

  - id: email
    smtp_server: smtpinternal.test.test
    smtp_username: ""
    smtp_password: ""
    from_address: no-reply@test.com
    smtp_cc:
      - test@test.com
    smtp_format: "{{data}}"
    subject: "Test&UseStartTLS=false"

Describe the use case of this feature:

This feature will allow to configure easily the UseStartTLS parameter.