550 5.7.1 Unable to relay
Posted on 2008-09-29
Remote users cannot send smtp email to users in other domains
If I configure John, a home user in Outlook 2007 using POP/SMTP John can send email's from home to any user in AD. But John cannot send email to other users outside the domain. If John log's on using OWA, John can send email to users in other domains.
If I enable "Allow messages to be relayed to these domains" under SMTP Connector Properties / Address Space it works as expected.
It appears the Outlook client is not authenticating. In Outlook 2007 I check "Log on to incoming mail server before sending mail". If I check "use same settings as my incoming mail server", outlook continuously prompts for username/password, all combinations fail to authenticate.
Note: We are using SBS 2003 with mydomain.local