To ensure optimum performance, our online email editor or email send API does not support attachments. However you can host the file on your website (or on a service like Dropbox) and then add the download link to your campaign.

Our two cents: Do not send attachments. Why? ISPs become suspicious when they see bulk emails sent regularly with attachments and may mark you as a spammer. Not to mention that some ISPs have file size limitations, your recipients email programs may block the attachments, and put yourself in your customers’ shoes: how many times do you open attachments in bulk mailings?

Instead of sending attachments, host the file online instead and insert the links in your email. Your deliverability will not suffer and you will be able to track the number of clicks by your customers.