OBIEE AgentID:_portal/ODI EXECUTIONS/TEST Exec [nQSError: 75027] Failed to open connection to SMTP Server (mail.server.com)

To resolve this problem in OBIEE:

telnet mail.server.com 25 

see the response that you get. If your mail server requires authentication then go to

1.  enterprise manager:
2. >> Business Intelligence
3. >>Coreapplication
4. lock and edit 
5. deployment
6. mail and enter the following:
1. smtp server : mail.server.com
2. port: 25
3. display sender: what ever you want 
4. username: emailid
5. password: password
7. Click Apply

If your mail server does not use authentication please look at my next post.