Discussion:
Ambiguous description on "reject_unknown_recipient_domain"
(too old to reply)
King Cao
2014-02-14 05:17:14 UTC
Permalink
Dears,

When I checked the description of "reject_unknown_recipient_domain" on
official portal: http://www.postfix.org/postconf.5.html, I found the
description is ambiguous with the implementation.

Below is the quote from portal:
*reject_unknown_recipient_domain*Reject the request when Postfix is not
final destination for the recipient domain, and the RCPT TO domain has 1) *no
DNS A or MX record* or 2) .......
From the description, If one domain has no DNS A record or no DNS MX
record, it will be reject as unknown recipient domain, however, the
implementation is:
It will check MX record first:
a) if exist, treat as known domain directly;
b) if not exist, check if A record exists;

So truth is that only reject if *no MX record and no A record*. Just my 2
cents.

Regards,
King
Viktor Dukhovni
2014-02-14 05:29:05 UTC
Permalink
Post by King Cao
*reject_unknown_recipient_domain*Reject the request when Postfix is not
final destination for the recipient domain, and the RCPT TO domain has 1) *no
DNS A or MX record* or 2) .......
English is not symbolic logic, but the intent is clear:

1. no (MX or A record)

rather than:

2. no MX or no A record.

By De Morgan's laws (https://en.wikipedia.org/wiki/De_Morgan%27s_laws)
the first is also:

3. no MX and no A record.

interpretation "2" seems too implausible to warrant correcting the
document, but if others feel it is ambiguous and someone sends a
patch for proto/postconf.proto that improves the clarity of the
text, it should be cheap enough to adopt it.
--
Viktor.
Noel Jones
2014-02-14 12:29:04 UTC
Permalink
Post by Viktor Dukhovni
Post by King Cao
*reject_unknown_recipient_domain*Reject the request when Postfix is not
final destination for the recipient domain, and the RCPT TO domain has 1) *no
DNS A or MX record* or 2) .......
1. no (MX or A record)
2. no MX or no A record.
By De Morgan's laws (https://en.wikipedia.org/wiki/De_Morgan%27s_laws)
3. no MX and no A record.
interpretation "2" seems too implausible to warrant correcting the
document, but if others feel it is ambiguous and someone sends a
patch for proto/postconf.proto that improves the clarity of the
text, it should be cheap enough to adopt it.
s/or/nor/



-- Noel Jones
Wietse Venema
2014-02-14 13:57:08 UTC
Permalink
Post by Noel Jones
Post by Viktor Dukhovni
Post by King Cao
*reject_unknown_recipient_domain*Reject the request when Postfix is not
final destination for the recipient domain, and the RCPT TO domain has 1) *no
DNS A or MX record* or 2) .......
1. no (MX or A record)
2. no MX or no A record.
By De Morgan's laws (https://en.wikipedia.org/wiki/De_Morgan%27s_laws)
3. no MX and no A record.
interpretation "2" seems too implausible to warrant correcting the
document, but if others feel it is ambiguous and someone sends a
patch for proto/postconf.proto that improves the clarity of the
text, it should be cheap enough to adopt it.
s/or/nor/
Did you mean: neither A nor MX record.

Clarity wins with "no MX and no address record."

Wietse
Noel Jones
2014-02-14 14:12:56 UTC
Permalink
Post by Wietse Venema
Post by Noel Jones
Post by Viktor Dukhovni
Post by King Cao
*reject_unknown_recipient_domain*Reject the request when Postfix is not
final destination for the recipient domain, and the RCPT TO domain has 1) *no
DNS A or MX record* or 2) .......
1. no (MX or A record)
2. no MX or no A record.
By De Morgan's laws (https://en.wikipedia.org/wiki/De_Morgan%27s_laws)
3. no MX and no A record.
interpretation "2" seems too implausible to warrant correcting the
document, but if others feel it is ambiguous and someone sends a
patch for proto/postconf.proto that improves the clarity of the
text, it should be cheap enough to adopt it.
s/or/nor/
Did you mean: neither A nor MX record.
Clarity wins with "no MX and no address record."
Wietse
Yes, I was thinking neither/nor, but "no MX and no address record."
is better.
We've obviously spent too much time discussing this already.


-- Noel Jones
King Cao
2014-02-15 06:35:57 UTC
Permalink
Dears,

Great, I found the official portal has change to "no DNS MX and no DNS
address record" which is better than before. Many thanks.

Regards,
King
Post by King Cao
Post by Wietse Venema
Post by Noel Jones
Post by Viktor Dukhovni
Post by King Cao
*reject_unknown_recipient_domain*Reject the request when Postfix is
not
Post by Wietse Venema
Post by Noel Jones
Post by Viktor Dukhovni
Post by King Cao
final destination for the recipient domain, and the RCPT TO domain
has 1) *no
Post by Wietse Venema
Post by Noel Jones
Post by Viktor Dukhovni
Post by King Cao
DNS A or MX record* or 2) .......
1. no (MX or A record)
2. no MX or no A record.
By De Morgan's laws (https://en.wikipedia.org/wiki/De_Morgan%27s_laws)
3. no MX and no A record.
interpretation "2" seems too implausible to warrant correcting the
document, but if others feel it is ambiguous and someone sends a
patch for proto/postconf.proto that improves the clarity of the
text, it should be cheap enough to adopt it.
s/or/nor/
Did you mean: neither A nor MX record.
Clarity wins with "no MX and no address record."
Wietse
Yes, I was thinking neither/nor, but "no MX and no address record."
is better.
We've obviously spent too much time discussing this already.
-- Noel Jones
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