Move addresses from To to Bcc?

[Pete Russell]

Its possible this is an MTA question and not an MS question?

Every day we see staff send email to customers and students in massive 
lists. Everyone the message is addressed to is listed in the To: field. 
Would it make sense to have a test for more than x entries in the To: 
field so move all of the addresses to Bcc: ?

If this did make sense would it be very difficult?

justathought
Pete