WE HAD THE SAME PROBLEM FOR A FEW DAYS. WE MADE ALL GUEST AND ANNONYMOUS USER ACCOUNTS DISABLED ON OUR EXCHANGE SERVERS (5.5). WE ALSO ENABLED SECURTIY LOGGING. IMMEDIATLY THE MESSAGES STOPPED AND WE SAW WHERE THEY WERE TRYING TO USE OUR GUEST ACCOUNT. THIS WILL FIX YOUR PROBLEM.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.