I was just looking at my Exchange queue and there are about 50+ e-mails all destined for domains ending with a .br address. Our company does little to no business with Brazil.
When looking at the message viewer all these have a NULL from address. The subject is a weight loss spam. How do I check to see if these are being generated from within a compromised server within my network or if they are originating from an external source.
Exchange 2010 SP3 RU1
Single Server with all roles.