Hope someone can help with this one.
Scenario is an internal Exchange 2003 server. OWA front end server in the DMZ. OWA logins work fine, with SSL configured.
Over the last week (3 times so far) when an internal person opens their Outlook and then tries to open an email with JPG attachments they are prompted for the webmail login. Why? Even if they enter their valid webmail OWA login it fails and reprompts once for each attachment. Once they get through the multiple login prompts, they can double-click to open the attachments, but they are all blank.
Any ideas on what could cause this? Why would someone accessing an email from an internal Outlook client get prompted for details of the OWA/webmail server login?