title: Creating server for sending mail with multiple sending ip-s
body: <p>Im trying to build a server that will be able to send mail from multiple ip-s depending on sending domain.</p>
  
  <blockquote>
    <p>We are using Debian 8 with postfix 2.11.3 and ISPConfig 3.0.5.4.</p>
  </blockquote>
  
  <p>How would i go and approach this problem? I have found some solutions like 
  <a href="https://serverfault.com/questions/650057/postfix-multiple-ip-smtp-banner">https://serverfault.com/questions/650057/postfix-multiple-ip-smtp-banner</a> But i cant make it work.Keep getting this error and no mails will work</p>
  
  <blockquote>
    <p>fatal: bind 121.121.121.121 port 25: Address already in use</p>
  </blockquote>
  
  <p>Can anyone who has managed to get it to work one way or another explain to me what must i do?</p>
  
  <p>For example we have website named site.com and ip 121.121.121.121 ...how should my postfix configuration look for that site to use that ip ?</p>
  
  <p>Ty in advance </p>