One of our customers is complaining that email is disappearing. On one occassion he claims that an email that was sent to him was never received. I checked message tracking on Exchange and was able to verify that Exchange Received and delivered that particular email. A few day later he read an email only to have it disappear when he closed it.
No one else has complained so we think that it is on the cllient side. I haven't seen his Outlook, (we are at different sites) but another tech walked him thru checking the settings on his Outlook and it seems clean. The customer uses at various time a ThinkPad laptop, iPhone, iPad and Mac Laptop to access his email.