Email Attachments
There's no support for sending an email attachment within Campaigns. A better method is to host external files that you want people to access and link to them from within the message content.
Email attachments are often used as a way of hiding viruses and malware. As a result, emails with attachments are more likely to be rejected or filtered automatically into the junk folder.
Large file sizes can also result in a higher number of bounced emails when attempting to deliver to ISPs where Users have lower inbox or maximum message size limits.
Attachments would also slow down delivery speed because of the increased overall message size, emails sent with attachments increases bandwidth usage dramatically and take much longer to send each individual message.
Users will generally prefer to receive a link to download a file because it means they can do so at their own leisure whereas attachments download automatically and this can seriously compromise the user experience for those on slower or mobile connections.
Workflow Email File Attachments
PDFs, images and .ics (calendar files) with a maximum file size of 200kb can be attached to Workflow Emails.
An attached file incurs an additional 1 Transaction charge each time the related email within the Workflow gets sent.