It's definitely a bug with Lotus Traveler, however I believe was able to work around it. (So far so good, but not celebrating yet)
The connections left open were to the primary mail servers of the end users listed in the address book.
By changing the primary mail server of the end users to the server Traveler was installed on I was able to work around the issue.
Not ideal, but better than telling the President of the company that he can't use his new iphone anymore.