2) Shipping to my clients using the field “BCC” (Blind carbon copy) the “CCO” (With Bcc) email program.
The difference is bigger than it looks. The system 2) is correct and the only one you should use.
If you use the system 1) You are revealing to each of your customers name and email address of each of the rest of your customers, demonstrate little knowledge you have of new technologies, and besides piss off your customers, it can cost you 3.000 euro fine. You will not be the first: Click here if you're curious to see the sanction decision of the Agency for Data Protection.
So, you know, when you send an email to a list of friends, customer, always use the COPY OCULTA.
NOTE: The company that received the 3.000 Euro sanction of the Data Protection Agency was NOT sent an email advertising. It was a Christmas card simplemnte. Maybe if it had been a commercial shipping, the penalty would be even greater.