Hello-- My Exchange admin and I are trying to get mail flowing to and from our test Exchange domain. I can access the test Exchange box from OWA and I can send and receive SMTP mail with it. I have ISA on a box by itself, in integrated mode. The message screener is installed on the ISA box, which is in my real domain. Exchange is on a separate box in a separate test domain. When we connect to the test Exchange server via POP or IMAP and try to send email off-site (that is, off the test domain), we get the following error: 550 5.7.1 Unable to relay for xxx@xxxxxxxxx (where 'xxx' is an address at Yahoo we're trying to send to). We're doing this from inside the network, using a machine on the test domain. If we use IMAP or POP (from the same machine) to send to another user on the test domain, it works no problem. I'll keep looking for what might be going on here, but meanwhile if anyone has any hints, they would be much appreciated. Thanks! Rob -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Rob Moore, MCSE Network Manager American Friends Service Committee 215-241-7870 rmoore@xxxxxxxx Our greatest glory is not in never failing but in rising every time we fall. --Confucius