Thanks John By the way I checked with my service provider. Their ISP does not block 25. But to successfully deliver SMTP mail, I need to use their relay server (it uses port 25 only). Where will I configure their relay server . Is it in /etc/postfix/main.cfor any other file. Do I need to modify anyting in dovecot or amavisd configuration??? Thanks Austin On Fri, Mar 15, 2013 at 9:55 AM, John R Pierce <pierce at hogranch.com> wrote: > On 3/14/2013 9:20 PM, Les Mikesell wrote: > > Some ISP's block port 25 if it is a 'home' type connection. Comcast > > recently started blocking and I can't connect there from home either. > > > configure your mail server to use your ISP's mail server as a > 'smarthost', OR configure it to use an external (coloc or whatever) > server as smarthost via port 587 with authentication. > > > > > -- > john r pierce 37N 122W > somewhere on the middle of the left coast > > _______________________________________________ > CentOS mailing list > CentOS at centos.org > http://lists.centos.org/mailman/listinfo/centos >