would it be this one?
'MailerUseSMTP' => false, // Whether or not to use a separate SMTP server for sending mail.
'MailerSMTPUseSSL' => false, // Whether or not mailer should connect using SSL (yes for GMail).
'MailerSMTPUseTLS' => false, // Same as above SSL setting, but for TLS. This setting will override the SSL setting.
'MailerSMTPPort' => null, // When MailerUseSMTP is true: SMTP server port (mailer will default to 25).
'MailerSMTPHosts' => null, // When MailerUseSMTP is true: A string host or array of hosts (e.g., 'host1' or array('host1', 'backuphost')).
'MailerSMTPUsername' => null, // When MailerUseSMTP is true: Authorized username for SMTP server.
'MailerSMTPPassword' => null, // When MailerUseSMTP is true: Authorized password for SMTP server (for above user).