I felt guilty when in this situation, but I think the guilt is misplaced. If you read therapy forums long enough, it becomes clear that this email compulsion is, if not universal, then quite common. It is an artifact of an hour per week of intimacy (quasi) and support followed by no contact. This is a recipe for inducing dependency.

I had a therapist who sent mixed messages about emails. Not too many, and not too long, she said, but her responses suggested something else -- that she lived for those emails because SHE needed them. She is a therapist because she needs to feel needed, and she gets a big hit of that in session, but needs smaller hits in between. So it was co-dependency and totally dysfunctional.