I am using php mailing list for sending out the emails. Now, i have discovered that phplist is not delivering the emails on the gmail addresses and getting the following message:-- SMTP error from remote mail server after end of data: host gmail-smtp-in.l.google.com [74.125.157.27]: 550-5.7.1 [174.120.237.148 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. b35si49670896ana.185 So, can anybody let us know the way out so that it will be delivered on gmail addresses?