Thanks for sharing this! I am not very familiar with highlevel.. but from what I'm seeing here in this guide, it looks like highlevel is using SMTP to connect to your other email accounts (Gmail, Amazon SES, etc.) and sending emails from highlevel using those connected email accounts.

If I've got that right, and you are effectively using another email provider to send email through highlevel, then really it's just about warming up that email address, which you can do with Boxward using SMTP / IMAP connection.

Guide on connecting SMTP / IMAP with Boxward - https://boxward.com/docs/how-to-connect-an-email-via-smtp-and-imap/

Let me know if that makes sense!