We have a customer site with an Exchange 2010 server (SBS2011) that does not receive email from a particular external domain. I have asked the sender from the domain in question to send in an email to the site and to copy me in on the same email. I receive the email with no problems (I am on a completely separate domain and Exchange 2010 server at a different site). I have used the Tracking Log Explorer to examine the mails received by the server at the customer site and there is no record at all of the email being received at that site (I did a very wide search for all mail received 1 hour either side of the time the email was received by me - just to be sure). It's my understanding that if there is no record of the email in the tracking logs, that it never reached the server. Is this correct?