Sending mail from one queue from all the users

Hi All, 

we have one requirements from the customer, that they want to send mail from one queue (commonly used for all the user). we have changed primary email ID for all the users, but still not able to send the mails if I select User name in the FROM field.

Note: If I select common queue for out going (FROM Field) it is allowing to send email.

can anybody suggest what are the configuration need to be done to achieve the same.

Regards

Harish