Hopefully not, only the unregistered version of MaxBulk Mailer adds a piece of text stating the version used has not been registered yet. This is to prevent using the software for real jobs without having purchased a license first.

The text looks like the following on 'Plain Text' messages:

----------------------------------------------------------------------

This email has been sent with an unregistered version of MaxBulk Mailer
MaxBulk Mailer is a new easy-to-use mail merge software for Mac/Windows

and it looks like the following on 'HTML' messages (Mac version):

Once you register MaxBulk Mailer your messages will only contain your contents. Actually it will be impossible for others to find out what software you have used to get your messages delivered.