Email multiple recipients without revealing other recipients

Question

I\'m using javamail to send emails to a list of recipients, but don\'t want them to be able to see who else received the email. I also don\'t want to send it using BCC sinc

Answer 1

The SMTP protocol doesn't care who's listed in the message and the recipients specified on the RCPT TO command are only used to figure out who to transport the message to. There's nothing stopping you from building the RFC822 message with the To header as you've defined above and then writing a custom SMTP client that send your particular message out but with a different set of recipients. And just because you can send the message doesn't mean a spam filter along the way is going to notice the wonky recipient headers and block the message.

In my experience, JavaMail's SMTP client is really good at sending basic messages without any of the mail tricks you often seen used by mailing list providers and spammers. Those companies spend a lot of effort to make sure they can send messages the way they want but they also are in a constant fight to make sure they're messages are treated as legit email.

Short answer: I'd resort to BCC and if this is for marketing purposes, consider using a company that specializes in this kind of thing.