? in outgoing emails in Outlook Web

Several of my coworkers have noticed a ? (question mark symbol) that appears in the outgoing email replies they send out (within the body of the email on the first line of the message). This only happens when accessing their email through Microsoft Outlook Web Access. The question mark does not appear in the message until after the email is sent. When going into the sent messages and looking at the message they just sent, a question appears on the first line of the body of the email message. Anyone have any idea what is causing this and how to fix this problem? This appears to happening widespread.