I was trying to figure this out too. I asked help desk, this is what i got: You can't send a file with our built-in tools. However, you can include a link in the email campaign that is sent to your subscriber, which clicks through to the file on your site. From there your visitors can download the file. You can learn a bit more about this in our guide here: https://support.squarespace.com/hc/en-us/articles/360041087192-Email-Campaigns-subscriber-verification As a note, For Newsletter Blocks and promotional pop-ups, you must enable at least one of these options: Subscribers verify by confirmation email after subscribing on your site (this is enabled by default) Subscribers fill out a Google reCAPTCHA when they subscribe That would mean that the initial email they receive would be a verification email, (if you went with that verification method).
Hope that helps. other people on forum think its easier to use outside services for this, not sure. I aleady paid for my email campaign so im kind of stuck using this.