In an update to Gmail's web interface, Google has added support for attaching files stored in Drive to your emails like conventional attachments. Before, you had no choice but to share Drive files as links or upload them yourself. This is especially useful when sharing files to people who aren't using Gmail and therefore don't enjoy the smooth integration with Drive that Gmail has. For those worried that Google would abandon Gmail with the recent focus on Inbox, this is encouraging news. Gmail continues to refine its already stellar web functionality.
By default, it will still attach Drive files as links, so you'll have to be sure to click "insert as attachment" in the pop-up window to add them as true file attachments. It isn't very difficult to do this, though, as the GIF above demonstrates. You also may consider attaching as a file even when sharing with fellow Gmail users, since deleting the file from your Drive account will remove their access if shared as a link.
Drive links will still be a superior option when sharing large files. The attachment size limit when sending as a file is still a meager 25 megabytes, while you can send files as large as 10 gigabytes through Google Drive links. When you intend to collaborate, at least via Google Docs, Sheets, or Slides, it will be better to use links too.
While Google has not added an exact copy of this function to Gmail's Android app, this is actually not nearly as unwieldy to do from an Android device. Google Drive is treated like a part of your file system for these purposes, so it is among your options for traditional file attachment. If you use "Attach file," you can still attach from Drive with most ROMs. Check out the screenshots below to see what I mean.
For those who use the web interface for Gmail, this is a pretty meaningful enhancement. You no longer need to upload files that you want to attach if they are already saved in Google Drive. If you have a data cap, getting rid of that redundancy will be especially satisfying. Hopefully, Google will increase the size limit on attachments soon as well.
Thanks Gmail on Google+