This is using MS Exchange server 2010 on MS Windows 2008 R2 server. Recently, in queue viewer, found quite a lot of stuck mail with empty sender address. Please refer to the attached file.
Is this some kind of spamming that want to send via my exchange server? How to stop it? almost all of these stuck mails have error message - 421 4.4.2 Connection dropped due to socket errors.
Thanks in advance.