On Mon, 2011-05-30 at 14:59 +0300, Timo Sirainen wrote:

On Mon, 2011-05-30 at 13:52 +0200, Hanns Mattes wrote:

...

is there a problem with the server, which is running this list, or do I have an issue with my DNS-server?

mail:/ # host 193.210.130.67 Host 67.130.210.193.in-addr.arpa. not found: 3(NXDOMAIN)

The IP changed last Friday and the ISP is being slow in adding the reverse DNS..

Looks like they finally added it.

On Mon, May 30, 2011 at 10:11 PM, Henrik Larsson dovecot-user@spambox.dkwrote:

which leads to postfix complaining:

...

May 30 13:28:39 mail postfix/smtpd[25014]: NOQUEUE: reject_warning: RCPT from unknown[193.210.130.67]: 450 4.7.1 Client host rejected: cannot find your reverse hostname, [193.210.130.67]; from=dovecot-bounces@dovecot.org to=hanns@hannsmattes.de proto=ESMTP helo=

If your are checking for reverse hostname and won't accept e-mails if this is not present you will reject a lot of legitimate mail.

This also stops more spam than the good mail it blocks, when people get blocked for this, they should complain to their ISP, why should we accept NON RFC compliant mail servers because the sys admin has not got around to reading dns 101?

Yes I know some ISP dont care and shrug their shoulders, I tell the people who complain to postmaster address to find an ISP who can set up their networks and cares about their users!

My employer does not pay me to sit here and update the whitelist files every 15 minutes because of some ISP who doesn't care about their users sending mail, and at my last employer a couple of years ago, we did the sums, 92% of spam stopped by rejecting no dns hosts! even here I still see it

mx-in1 ~$ cat maillog | grep -c "cannot find your hostname" 5328

mx-in2 ~$ cat maillog | grep -c "cannot find your hostname" 7041

in only 20 hours since logs rolled!!!!!!!

enjoy your spam :->

Am 30.05.2011 14:11, schrieb Henrik Larsson:

If your are checking for reverse hostname and won't accept e-mails if this is not present you will reject a lot of legitimate mail.

No problem here, using the Postfix-restriction reject_unknown_reverse_client_hostname

Regards Hanns

Am 30.05.2011 15:12, schrieb Tom Hendrikx:

On 30/05/11 15:00, Hanns Mattes wrote:

...

Am 30.05.2011 14:11, schrieb Henrik Larsson:

...

If your are checking for reverse hostname and won't accept e-mails if this is not present you will reject a lot of legitimate mail.

No problem here, using the Postfix-restriction reject_unknown_reverse_client_hostname

I just saw a complaint regarding some possible DNS issue on someone's mail server. The person who was asking around, had some issue with not receiving e-mails from a valid mailing list that he was subscribed to.

His name looked just like yours :)

:-)

Nevertheless: There WAS a DNS-Issue on someone's mail server. And I'won't give up one of my most effective Anti-Spam measures, because an ISP ist slow in adding a reverse DNS.

Yes, there is as risk of false positives, if you try to block spam (though in this case, it is no false positive at all), but what is the alternative? Stop blocking Spam? I don't think so.

Regards Hanns