This is using MS Exchange 2010 Server. Sometimes, I browse to the queue viewer, and always found few mails were attempt to be sent to some very strange recipeints. However, these type of mails always stuck, and kept but die off after 2 days. To my surprise, the sender address is "<>" (see the attached jpg). What was happening, and why so many such mails were sending out? What can I do to stop this?
Thanks in advance.