blind copy not sending with email

Blind copy not sending with email. Do not know if there is a sitting that needs sit or what is the problem. Tried many times with a number of email address. 

The only setting is in Menu > Tools > Accounts, then on the General tab for your account.

If you add an email address in that field, a BCC copy of every email sent using that account should go to that address. Make sure there is no error in the email address.

Or did you mean just occasionally using the BCC field when composing an email?

I sent out the same email to 3 or 4 customers at a time so I want to blind copy the email to the others customers. I do not want my customers to have the email address of the other customers.

Then enter the email addresses in the BCC field indicated above.

I did enter the email address of the customers I wanted the email to go to in the BCC. The email addresses in the BCC did not get the email. The only one that got it was the email address in the TO field. Thank you for your help