ENH: option that receivers do not see each other (but not BCC)

[peircej]

Is your feature request related to a problem? Please describe.

To use redmail for sending out a newsletter to all my users, I need them each to be the To: field but not to see each other's email addresses.

When using smtplib the recipients are not all added to a single email - they cannot see each others' names - whereas in redmail they are. That means I can't send an email to 1000 recipients without sharing all their emails (GDPR breach)

Describe the solution you'd like

I would like the option (and preferably the default) to be that recipients don't see each others emails

Describe alternatives you've considered

I could use BCC but that looks bad.

I could loop over them

for recip in recipients:
        email_sender.send(
            subject=subject,
            sender=sender,
            receivers=[recip],
            text=msg_text,
            html=msg_html
        )

but that seems like a lot of compiling the email for each of my recipients

I haven't looked to see how smtplib achieves this preferred outcome (maybe it does run a loop under the hood) but, for now I'll have to stick with that.