When sending a mass email it is never good to have an attachment because the odds of going into SPAM is extremely common..
What you should do is store the attachment on dropbox or google drive and then hyperlink text in the email where people can click to download.
Here are the steps to do this is Google Drive:
Upload this file to Google Drive
Click on the file once it is uploaded to Google Drive (so that it is highlighted)
Click on the share icon (on the top right) in Google Drive and copy the URL (which is provided)