My firm has problems receiving email from a particular domain. For awhile, email from AOL was not getting through but now it is. I can only identify one particular domain that email does not get delivered and it is returned as “undeliverable/user unknown” attached. We use Exchange 5.5 SP3 and have a Pix 506 firewall. I can find no obvious evidence that the messages ever made it to our Exchange server but my knowledge of Exchange is limited. My vendors (ISP,Hardware) all insist that it is an Exchange problem. Any suggestions as to why some email will get through (AOL) and some will not at all? Where do I start? Thanks!
