my email diaspora.yml snippet for my Diaspora* POD - on my server I use 'Postfix'

diaspora.yml

 ## Setup E-Mail
  mail: ## Section

    ## First you need to enable it ;)
    enable: true

    ## Sender address used in mail send by Diaspora
    sender_address: 'sal@qaligo.com'

    ## This selects which mailer should be used. Take 'smtp' for a smtp
    ## connection, 'sendmail' to use the sendmail binary or
    ## 'messagebus' to use the messagebus service.
    method: 'smtp'

    ## Ignore if method isn't 'smtp'
    smtp: ## Section
      ## Host and port of the smtp server handling outgoing mail.
      ## This should match the common name of the certificate
      ## the SMTP server sends. If he sends one.
      host: 'localhost'
      port: 587

      ## Authentication required to send mail. Use one of 'plain',
      ## 'login' or 'cram_md5'. Use 'none' if server does not support
      ## authentication
      authentication: 'plain'

      ## Credentials to log in to the SMTP server - may be necessary if
      ## authentication is not 'none'
      #username: 'changeme'
      #password: 'changeme'

      ## Automatically enable TLS? Ignored if authentication is set to none
      #starttls_auto: true

      ## The domain for the HELO command if needed
      domain: 'localhost'

      ## OpenSSL verify mode used when connecting to a
      ## SMTP server with TLS. Set this to none if you have
      ## a self signed certificate. Possible values:
      ## 'none', 'peer', 'client_once', 'fail_if_no_peer_cert'
      openssl_verify_mode: 'none