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?

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

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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".