I have setup an Ubuntu 6.06/ISPConfig server using Falko's excellent howto and the the ISPConfig installation guide (which is also excellent) and all has been working well. I can send and recieve email through the webmail interface and recieve mail with Outlook Express. My problem comes in sending email through Outlook Express. I get this response: This area's largest DSL provider blocks port 25 - and I am testing from that provider's service. So I suspect my access to the server is being blocked. Plus, I cannot see any evidence of a login attempt in the server logs. The provider says that I should access any off-network mail server using port 587, but if I change the smpt port from 25 to 587 (in OE) I get this: Is it possible to send email through the ISPConfig based domain's email server from outside its network?