Email attachments, while sometimes necessary, should be considered carefully. Even the most carefully designed PDF will often pose an accessibility issue for users of assistive technology. PDF is rarely the best format for distributing information electronically. Consider including the email text information rather than asking the user to download a PDF or consider linking to a web page. Using email and not a PDF will make your email more accessible. Furthermore, the recipient's email service provider is less likely to be identified as spam, less likely to be perceived as a possible security risk, and is more likely to be read by the intended recipient.
If you must include an attachment, be sure to give it a meaningful filename, communicate in the body of the email exactly what the attachment is and the type of information it contains.
For more information about creating accessible emails, see Make Your Outlook Email Accessible to People with Disabilities