It seems like a strange ida at first but, as Google explains it, it might be handy at times to be able to attach emails to emails.
We’ve heard from you that there are situations where attaching emails makes more sense than forwarding separate emails, like wanting to forward multiple messages related to a single topic. With this new functionality, you can do exactly that. Sending emails as attachments allows you to write a summary email message to your recipients, and attach the set of supporting emails that recipients can directly open in their mail client. – Google blog post
In the post, Google said that “You’ll know this feature is available to you when you see the “Forward as attachment” option in the three-dot More menu.” You can attach as many emails as you like and when you click on a .eml email attachment, it will open in a new window.
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