swiftmailer:
    transport:        smtp
    username:         user
    password:         pass
    host:             example.org
    port:             12345
    encryption:       tls
    auth-mode:        login
    timeout:          1000
    source_ip:        127.0.0.1
    local_domain:     local.example.com
    logging:          true
    spool:
        type: memory
    delivery_addresses: [single@host.com]
    delivery_whitelist:
        - /foo@.*/
        - /.*@bar.com$/