Hello, My name is Paul Bonnemaijers from the Netherlands and i've followed the guide of Falko for installing CentOS 5.7 + ISPConfig 3. Great guide BTW! I'm currently experiencing the following problem's with sending mail via Outlook. The error i get is: Your message did not reach some or all of the intended recipients. Subject: test Sent: 24-11-2011 9:48 The following recipient(s) cannot be reached: [email protected] on 24-11-2011 9:48 Server error: '554 5.7.1 <[email protected]>: Relay access denied' and another one is: Reporting-MTA: dns; duskwood.domain.nl X-Postfix-Queue-ID: A2C664368603 X-Postfix-Sender: rfc822; [email protected] Arrival-Date: Thu, 24 Nov 2011 09:53:10 +0100 (CET) Final-Recipient: rfc822; [email protected] Original-Recipient: rfc822;[email protected] Action: failed Status: 5.0.0 Remote-MTA: dns; mx.mailserver.com Diagnostic-Code: smtp; 550-rejected because 1.2.3.4 is in a black list at zen.spamhaus.org 550 http://www.spamhaus.org/query/bl?ip=1.2.3.4 For problem one i have no idea how to fix this. For error 2 i checked www.spamhaus.org and it appears because i'm running the server @ home on my internet connection this is automatically blocked unless i turn on SMTP authentication in my email client. I checked the box in the Outlook account: My outgoing server (SMTP) requires authentication. and selected the option "Use same settings as my incoming mail server" I still got the message back and spamhaus said the following: If you are absolutely sure that you have SMTP Authentication turned on properly in your email program, then contact the administrator of the mail server you are trying to send your email out through. It will usually be your ISP's mail server or your company's mail server. Ask them to check your "SMTP Authentication" settings. Things to check: Are your outgoing mail server account, username and password correct? (check them, and remember that passwords are case-sensitive) Is the SMTP authentication working correctly at your mail server? (ask your ISP to check) Make sure you are connecting to your mail server's 'authenticated mail' port 587 and not the ordinary 'unauthenticated' port 25. (ask your ISP to check for you) Mail servers only run spam filters such as Spamhaus PBL on port 25, so if you find you are being blocked by the PBL when you try to send mail to your mail server that means you are not communicating with the mail server on the 'authenticated' port 587 but you're still on port 25. This means your 'SMTP Authentication' is not working correctly. (ask your ISP to check for you) How can i check above things? I've already checked the following: Username/Password (asuming that they are the same as login on the POP3/IMAP side) Don't know if SMTP authentication works properly Cannot connect through port 587 even though i've forwarded it on my router When i try to send a test e-mail to myself or from another account it works properly! Is there anyone that can help me out with these 2 issues? Then i will have a perfect server running! p.s. the mailserver needs to work properly on different domains (i have 4 domains) and mailboxes. I hope this is possible. p.s.2 the ip-adresses and e-mail addresses are masked With kind regards, Paul Bonnemaijers