For non-customized bulk email, is it better to use the BCC field, or generate a separate email with To header for each recipient?

I'm generating a bulk mailing each day for users who want to receive the daily deals. I can either send a separate physical email with each user specified on their own unique To header, or I can send one email with all the users on the BCC line.

Obviously if I ever want to create user specific content I will need to customize the emails per user and send them individually, but if I don't want customized email right now, should I just send out the single email with everyone on BCC? Any reason to NOT do that.

Edit: I'm using a third party as my gateway that specializes in delivery with CAN-SPAM compliance, etc.. not trying to do this off my own mail server...

Update: I guess I'm really also looking for some metrics here. Is there a difference in open rates of BCC'ed email vs To field email? What about spam filtering rules that might pre-classify bas开发者_高级运维ed on the BCC field?

No reason I can think off for NOT doing it. Using BCC is the polite way to send bulk emails.

In this case, it turns out that the correct answer was neither. The gateway provided a custom header API that allowed me to specify all the recipients in a secondary "To" field. The API then handled the blind delivery of the emails, and also did variable substitution for me so I didn't have to transmit all the duplicate content multiple times. The API then handled doing "best practices delivery of the email".