I am using the default set up of send mail in a CentOS box and I have an php application that uses the PHP mail function. For past few days while testing, I see that the mails from this application are in the SPAM box. I tested it with gmail and hotmail, it is the same in both cases.

Do I have to modify or change something in Sendmail configuration to make sure the mail is from an authentic server? I read from somewhere that if we send emails from unreachable hosts it will be marked as SPAM...but I do remember the mails were reaching INBOX initially and only past few days it is marked as spam.

Any advises or pointers on this would be greatly helpful.

• configuration
• sendmail
• spam
• php

I had similar problem while sending mails using php mail i resolved this by including header argument in the code

   <? 

         $header="-F 'Webmaster' -f support@yourdomain.com";
        mail("recipient@recipient-domain.com", "Test Message", "This is my message.", $header); 
    ?>