Re: Mail Submission Protocol

[Dave CROCKER <dhc2 () dcrocker net>]

On 4/21/2010 6:49 AM, Claudio Lapidus wrote:
> So we are considering ways to further filter this traffic. We are evaluating
> implementation of MSA through port 587.


RFC 5068, Email Submission Operations: Access and Accountability Requirements, 
is a BCP.  It specifies authenticated port 587 for email submission across the 
net.

As others have noted, it works well through a wide variety of access 
environments.  I don't remember the last time I found it blocked.  I use it over 
TLS, of course.

Blocking of outbound port 25 for all hosts not explicitly authorized has become 
common.  The fact that 587 default to authenticated is the win.

d/
--

  Dave Crocker
  Brandenburg InternetWorking
  bbiw.net