The "New Look" Acrobat is terrible. There's no way to send a PDF in an email as an attachment and the tools are not easily accessible. Very poor design. I finally figured out how to revert back to the old look and everything is now there. Stop overthinking things.
We acknowledge that the new Acrobat represents a notable change; however, we hope that as you get familiar with the new interface, you can be more productive and get more out of Acrobat.
To enable, sending PDF as attachment, please go to Edit or CTRL+K (Windows) > Adobe Acrobat (Mac) > Preferences > Email Accounts and uncheck 'Always send file as a link' > click OK and reboot the computer