Joe Provo wrote:
On Thu, Jun 18, 2009 at 03:36:44PM -0400, Zhiyun Qian wrote:
It has been long heard that many ISPs block outgoing port 25 for the purpose of reducing spam originated from their network.
Yes, it is standard practice for non-server accounts and most dynamic-only accounts; only allow unauthenticated smtp traffic to your own smtp servers. If you are not running server-to-server traffic at the end of that broadband pipe, then you should be shifting your userbase to authenticated on the SUBMIT port [587] anyway...
The Messaging Anti-Abuse Working Group (MAAWG) published recommendations for managing port 25 traffic a few years ago, and even then it had already been a widely-accepted best practice for nearly a decade. http://www.maawg.org/port25 -- J.D. Falk Return Path Inc http://www.returnpath.net/