I’m using one To address and lots of “Bcc”. Only issue is that randomly one of the email addresses is shown in the email headers! Here’s an example (I’ve commented out private info).

Received: from **IP-ADDRESS** ([**IPADDRESS**]) by
**DOMAIN**.emailfiltering.com with emfmta (version **NUMBER**) vanilla id

If I send another email a different Bcc address is used. Any ideas?