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Re: [ietf-smtp] Private Domain Names and the EHLO/HELO Command

2013-03-26 20:21:01
Agree, which is why I got the Thunderbird folks to add a fix for the machine name configuration so it can be hard coded to the NAT public address.

In the mean time (and for the general others), for a submission server, I suggested that the EHLO required check allowed by a submission server be relaxed on the basic idea that eventually AUTHentication will take place as required by a submit server. So that is what we have - For port 587 operations, since AUTH is required, the EHLO check is skipped.

For a dumb or any client really , at the very least it (ehlo/helo value) needs to be manually settable or as I stated like Outlook will do, use a undotted name like the machine NETBIOS name, if any. I think most clients will not bother (it can't, nothing to solve).

I am just suggesting what might be the least harmful.

- If you use brackets, you must consider IP checking will be done.
- if you use dotted names, you must consider some DNS/IP checking domain matching will be done, although enforcement is not practiced at this point.

Either it allows for manual setup for an IP literal or a NAT router public domain or use a netbios/undotted name, one that will not add overhead for receivers believe it can check it.

On 3/26/2013 8:55 PM, Steve Atkins wrote:
On Mar 26, 2013, at 5:50 PM, hector <sant9442(_at_)gmail(_dot_)com> wrote:
2) If squared bracketed, by specification assume a dotted IP address and by 
SMTP specification this allows for a simple SMTP compliancy check to verify the 
IP of the connection matches the provided IP literal.   You are allowed to do 
this because when a IP Literal is presented, it MUST machine the connected 
client IP address.  This yields a pretty high spam rejection with 100% zero 
false positives after at least 10 years of automated operations.
It'll fail all the time in the case of an MUA behind a NAT - which is going to 
be pretty common in the case we're discussing of a dumb SMTP client submitting 
to a smarthost.


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