Thanks for your concern. We have implemented the list view value as 'does not contain' wherever appropriate for the fields. For.e.g., for Email field, Company field etc.
Please verify at your end and let us know.
Also, your feedback is valuable to us. Please provide more feedback/comments in that manner we can enhance the MassMailer for all the users.
We want to see you happy.
When I am trying to create a new View while going visiting Mass Email Wizard --> Select Object(Step1) --> Specify Recipients(Step 2) --> Create a New View --> Specify Filter Criteria --> Operator is not containing 'does not contain' as a List Value in the list. Is there any way we can get wherever appropriate?