Gmail update lets users send emails as attachments2
Another method to insert emails in a new thread to select the emails from the Gmail inbox and then choose to “Forward as attachment” from the three-dot menu. You can even reply to an email by adding multiple emails in the compose window via drag and drop.
The new feature revealed by Google today will be available to all Gmail users, not just Gsuite members. However, according to Google, the rollout may take up to 15 days starting on December 9, so everyone should get it by the end of the year.