It is possible to set testMode@org.sakaiproject.email.api.EmailService=true in sakai.properties, causing all emails that use the sakai email service to be sent to the logs. However, mailtool sends out emails independently of this service, thus will still mail out. There may be an expectation that this mode will cause _all_ emails to go to the log file - e.g. for test sakai instances - so this may be an unwanted surprise. Perhaps mailtool should honour this setting and send to the logs too?