ingress SMTP

Winders, Timothy A twinders at
Wed Sep 3 12:08:17 CDT 2008

On 9/3/08 10:50 AM, "Suresh Ramasubramanian" <ops.lists at> wrote:

> On Wed, Sep 3, 2008 at 8:46 PM, *Hobbit* <hobbit at> wrote:
>> What I'm trying to get a feel for is this: what proportion of edge
>> customers have a genuine NEED to send direct SMTP traffic to TCP 25
>> at arbitrary destinations?  I'm thinking mostly of cable-modem and
> Not too many - they got themselves port 587 to submit outbound mail.
> Read the maawg managing port 25 document - and while you are at it
> read the walled garden doc too.. port 25 abuse is the least of your
> worries with cable/dsl cpe swamps
> --srs

We have not setup a port 587 smtp submit server.  Our smtp servers run only
on port 25.  We point our clients outbound email to these servers, which
require authentication for relaying.

We run into problems with ISPs and hotels which block outbound SMTP.  They
can't send email.  We have to work with them to work with their ISPs to find
out what SMTP server they can use for outgoing email.  It's a big problem.

Yes, setting up a 587 submit server internally would be best, but man power
is at a premium and it hasn't happened.

So, for us, having ISPs block port 25 is a problem.

=== Tim

Tim Winders | Associate Dean of Information Technology | South Plains

More information about the NANOG mailing list