Some people in the work are complaining us that they receive emails twice from one user. But he is sending only once.Please help

Delete cache (ost file) on user's profile.alfa21

Hi, Do the issue only happen on specific email or all emails from that user? Can you reproduce the issue? Please try to send a test email, then check the result via OWA, if the issue disappears, the issue can be caused by your mail client. What's your Exchange version? What's your mail client? Please also use message tracking to locate the problematic email and see if some abnormal things there. Thanks, Elvis