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 based on the BCC field?
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".