Email blasts are typically set-up to go out automatically on a recurring basis. However, if you would like to send out a one-time announcement with an attachment you can do this using the Send Announcement feature within your Email Blast settings.
You can access your Email Blast settings by clicking on your name and selecting email blasts from the dropdown:
Then click the Send Announcement button, add a message, and an attachment if desired:
Clicking the send button will blast your announcement to your entire list of email blast recipients.
You can access the PDF of your listings by clicking on the Download Report button and selecting Email Blast:
You can also attach things like showsheets if you want to highlight a specific property. Check out this article for details on creating a showsheet in Nestio.