Javelin supports tracking of respondents when you use the built-in communications manager. For non-anonymous forms, each respondent gets a unique URL when emails are are sent out from Javelin. If you want to use an external system to send emails and track the respondents, you have to add a "Hidden Field" to capture the email of the respondent. The form you create will be an anonymous form. You can then pass the value of the email tracking field by appending it to the form URL.
The format to use: Form-URL&hidden-field-name=email-address
An example URL is shown below