Thanks for the feature request. This will be a nice feature which will enhance our Mass Mailing Functionality. We will keep you posted once this will gets implemented.
Mansa Support Team
I have used your Mass Email Functionality and I am pretty much comfortable with this module. You guys did an excellent job in order to built this feature which is nearby similar to Salesforce Mass Mailing minus Salesforce Mass Mailing Limitations. Here I would like to request you guys if you can setup multiple global email addresses, that can be selected in a dropdown before sending the mass emails.