I have a few blogs on W.a all under the same Pro account, and I just enabled Write.as Letters for Dev Journal (https://write.as/dev-journal), but when I post the shortcode for e-mail subscriptions in the signature, it is blank. Found it odd, or maybe I am just doing something wrong? I am sure I enabled e-mail capabilities on the toggle, and the other things I wrote in the signature (incl other links) work just fine.
Just pointing this out. Thanks for looking into it