You can deactivate the sender’s info for the selected or all the contacts in Mass Mailing News .

First, click on the “Contacts list” tab and, from the “Tools” menu, select “Deactivate the sender’s info for the selected or all the contacts" and select “For the selected contacts only” or “For all the contacts” and confirm your choice.
Note: The sender’s information, to which we refer to, comes from the third tab of the “Contact form” dialog box. On the “Contact form” dialog box, see the section related to the use of a customer representative for mailing messages.