An email attachment is a computer file sent along with an email message. One or more files can be attached with a link to any email message, and be sent along with it to the recipient. This is typically used as a simple method to share documents and images (PDF files, JPG pictures, or Office documents).
Because of security risks by email attachments, access by certain email clients with certain file extensions will be initially blocked. Furthermore, can the spam scoring in spam filtering increase by adding attachments so that emails are filtered as false positives. Thats why eyepin recommends using links in your mail, to reduce the size of your mail and prevent spam.