all emails going into to-do list---Outlook 2007

This is a question about Outlook 2007 To-do list. I am the IT person for my
company.

I have a user who is having all his emails automatically going into the To
Do list, under "No Date". He hasn't flagged the messages but they still go
into the To Do list. Strangely, he claims "it does it like once a month".
Thus, he will suddenly have a whole bunch of task reminders suddenly appear
for all these emails.

I am familiar with Outlook 2003, but haven't done much with 2007 yet. Can
anyone advise on what I need to do to correct this? Thank you!