Should I Be Offended? Insulted?

I was having an email discussion with one of the commenters here and I got this statement in response to one of the emails I sent:

"Its obvious you had someone write this email for you; if not at least dictate much of the verbiage."

Excuse me?

It gets better...

He goes on to say:

"Don't really know who wrote that email for you, but I'd appreciate it if they'd show the courage to at least reveal their identity. Or, at least communicate with me that you are getting help (a lot in this case) from a friend."

I don't know whether to be completely offended that my character has been called into question, or just laugh. I've never been accused of being a plagiarist before.