Agreed about it sounding like an account already exists which is odd. The e-mail is never hitting our e-mail gateway, before it could even get classified as SPAM. It's not getting bounced, rejected, or held. Other users receive e-mail from Evernote and if we use a different address/alias, the invitation e-mail arrives. There is something with her e-mail address specifically, but we're at a loss for how an account could exist already when we just created it recently.
Thanks for your input!