We have a SBS 2003 server with exchange. In the majority of cases emails that are sent from the organisation are being received by external recipients.
However in a few cases the exteneal recipient is not receiving any emails from us. We are not getting any undelievererable errors, so the only way we know that the recipient is not receiving them is by speaking to them on the phone.
I dont think that the messages are going into the recipients junk email folder.