Using Bananatag's SMTP Relay you can track outgoing emails through Mozilla's email client Thunderbird without the need for any additional software.
Setup is simple. To start, you will need a Bananatag account, which is available for free at Bananatag.com.
Once you've created have your account, log in to Bananatag and select Account and then Settings from the left hand menu, then click Email Relay on the main window.
Under the SMTP Relay settings, enter your desired password and select Save New Password. You'll receive a confirmation (as above) with the correct SMTP settings for your account.
SMTP server: smtp.bananatag.com
Note: If you do not have Send Direct set up you will be prompted to enable it before continuing.
Open Thunderbird's account settings by right-clicking on your email address in the left column. When the new window appears click on "Outgoing Server (SMTP)" and then "Add..." on the right hand side.
On the SMTP Server window you should have the ability to add new settings for the new SMTP server you would like to use. Enter your Bananatag email address for the user name and the SMTP Relay settings mentioned in Step 1.
When the Bananatag SMTP Relay is set to the "Default" outgoing SMTP server all emails send through this address in Thunderbird will be tracked. To not track with it simply return to your email address settings in Thunderbird and change the "other" outgoing server to "Default". In the above example the regular un-tracked server is "Google Mail".
Note: Upon sending your first tracked email you should be prompted to enter your password for the SMTP Relay. This is the unique password created in Step 1. If this prompt does not appear you may need to close Thunderbird completely and open it again.