This functionality will eliminate the need to download or copy emails before adding them to other emails.
It will also make it easier to send multiple messages in a single email, instead of having to forward each email separately.
Drag and drop
Gmail users will be able to drag and drop the emails they wish to forward directly into an open message draft menu.
This will convert the attached emails into .eml files. Once one of these are clicked, the attached email will open in a new window.
Alternatively, users can select the "Forward as attachment" option when they click on the "More" menu on individual emails.
There appears to be no limit to the number of emails you can attach, and Google has said that the feature will let you attach "as many emails as you'd like".
Google noted that the feature will be rolled out "gradually".
To see if this feature is supported on your account, look for the "Forward as attachment" option as mentioned above.
The gif below illustrates how the new feature works.