Can’t see message from this person

This is another weird one. Person A (on Groupwise) sends Person B (using Outlook Express) an email and the only info missing is the body of the message. When Person A sends the same email to Person C, who works with Person B and also uses Outlook Express, everything is fine. Person C can then forward the email to Person B and all is well. There doesn’t appear to be any special rules set up anywhere to prevent this. Anyone have an idea out there?