We use Ubuntu Server and in a days I have installed and configured Postfix+Dovecot+MySQL as it is explained here. From that tutorial I escaped creating certificates and antispam application. Right now it works good but when I try to send an email to GMail I am getting back my email with following content:
Reporting-MTA: dns; ns1 X-Postfix-Queue-ID: 19FDD1EA1826 X-Postfix-Sender: rfc822; email@example.com Arrival-Date: Tue, 27 Sep 2011 14:05:35 +0500 (TJT) Final-Recipient: rfc822; firstname.lastname@example.org Original-Recipient: rfc822;email@example.com Action: failed Status: 5.7.1 Remote-MTA: dns; gmail-smtp-in.l.google.com Diagnostic-Code: smtp; 550-5.7.1 [18.104.22.168 1] Our system has detected an unusual rate of 550-5.7.1 unsolicited mail originating from your IP address. To protect our 550-5.7.1 users from spam, mail sent from your IP address has been blocked. 550-5.7.1 Please visit http://www.google.com/mail/help/bulk_mail.html to review 550 5.7.1 our Bulk Email Senders Guidelines. w3si6844977eej.200 Our system has detected an unusual rate of 550-5.7.1 unsolicited mail originating from your IP address.
I tried to send to another outside domain and my email had been sent successfully. What can I do to resolve this problem?