Send files as attachment from Google Drive.
Select files in Google Drive and send them as attachment in Gmail.
Select several files on your Drive and « Send to » will attach them as single file to a draft on your Gmail.
« Send to » support Google Documents, Google Sheets and Google Presentation. Google docs will be attached as pdf to the email.
Files uploaded to your Drive will be attached to the draft email in their own format.
Buy the license right from the app after installing it.