Precautions while using Securing Email
Individual Gmail messages including attachments may be up to 25 MB in size. However, users can send files of up to 15 GB in size through Google Drive. Effectively, the files are stored on Google Drive and only links to them are sent. This means that the recipients can access the file only if it is shared with them on Google Drive. Gmail notifies the user if the file being sent is not shared with the recipient and allows the user to modify the sharing settings before sending the file. The files can either be made accessible to anyone with the link, or shared privately with the email recipients. The latter does not work if the recipients do not have a Google account or if the email address receiving the message is not associated with Google.