Earlier quoted context omitted.
I think it's the "external" part of the phrase that's a problem, not the "multiple". She could've sent it to one external party and that still may have been a fire-able offense. (Of course, this depends on what she was sending, if it was really protected information, and who she was sending it to. If she was sending evidence of criminal wrongdoing on the part of Google to her lawyer or a government official, then I d…
An external party could be her own email account at a different service. Probably because she was worried that something exactly like this would happen.
I remember an all hands where someone forwarded a relatively innocuous email to her Yahoo, once, and we all received a big reminder.