Hi

Our mail server is Postfix 2.2 running on CentOS 4.7.
It was working fine since last few years. Suddenly no user could send mail using this server. The sent message is getting bounced with the following message ( in postfix logs ) :

550 Administrative prohibition (in reply to RCPT TO command)

On speaking to our mail service provider, they say that they have added some authentication and needs to be done on our internal mail server.

Can any one help in getting the same sorted out ?


Thanking in advance
rajesh.bahl

You are relaying your mail through your providers SMTP server, which is an acceptable practice. Some providers don't require authentication on their networks, others do. Apparently your provider did not require authentication and changed it so that it does. On a (per email transmission) access basis, YOUR server will need to authenticate to their server. Postfix does support this and there is plenty of information available and a search of keywords such as "postfix, relay, SMTP, authentication" should get you started. You will need to get or create the authentication credentials from your ISP in order to do this, which will likely mean setting up an email account / user name and password for your Postfix server to use.