This is the only way of doing that, however it can be seen as a large security/privacy issue.
Myself I'm pushing for "notify an admin"/"report spam" features for PM's for just this type of thing, as it'd ensure user privacy.
Also, your members will know you read their pm's if unread pm's come up as read
also, viewing pm's via phpmyadmin is a waste of time; nothing beneficial, and it'd actually take longer.
