We have a company wishing to send us an email but for some reason their emails do not get through - they get a bounced back message after a day or two saying that the server was unreachable. I have checked our Exchange settings and can find no reason for the messages to be rejected from us. Our ISP claim the messages are not getting to them so I've asked the sender to check with their ISP to see if they are getting out. Is there anyway I can trace where the message is being relayed to/from so I can find where it gets lost? I suspect there may be some blacklist IP address or something somewhere blocking this. We can send to them OK and they can send to everyone else except us. Any ideas? Thanks Dave