Gmail now has the ability to upload multiple attachments at once, rather than one-by-one. Additionally, when you attach files, you’ll now get a progress bar indicating how long until the file is uploaded and ready to be sent.
Now, Gmail essentially works like any other service on the Web that lets you upload files. When you click “attach a file” when composing an email, you can browse your computer and select multiple files by holding down the CTRL key on Windows machines, or Cmd on Mac. Once you’re finished, Gmail starts uploading and keeps you posted on the upload status.