Gmail lets you attach all sorts of things to emails; images, documents, and anything else you can package up as a file on your computer. That's not all—Google heard you like emails, so now you can send an email inside another email (yo dawg). Yes, you will soon be able to send email threads as attachments in Gmail.
This feature will be familiar to anyone who's spent time in an office that uses Outlook. Rather than forwarding email chains separately, you can compose an email explaining why the emails are important, and then attach them at the bottom. Recipients will be able to open the forwarded emails (they'll be .eml files) inside Gmail without downloading anything.
Gmail will support forwarding unlimited emails, which might end up a bit overwhelming. This feature isn't live yet, but the rollout will start today on "Rapid release" G Suite domains. It could take 15 days before that release is done, but more users will begin seeing email attachments next month. You'll know the feature is live when "Forward as attachment" appears in the overflow menu on messages.