What happens if a DNS blacklist is offline?

HCL Domino Domino Forum
1

Hi,

I had strange problem. I wrote another DNS blacklist to my configuration document. But I made a mistake in it’s name. The reason was, that Domino was rejecting ALL!!! incomming mail messages.

Is this a bug?

Will this happen if some DNS blacklist listed in my configuration will be down? (If yes, I can not use DNS blacklists - it’s too dangerous)

I am running Domino 6.5 on Linux RedHat 9.0.

Thanks for answer

2

Subject: What happens if a DNS blacklist is offline?

I have answered this before here - you could try a search on this forum.

Briefly, if a DNSBL is down the result may be the same as if it is up and the host you are looking up is not listed in it (that is, you will accept email). If the list is down transiently, you may not even notice because parts of the list will be cached by your DNS server or servers further up the delegation tree.

UNLESS 1) The DNSBL has been taken down by its administrator and in order to encourage people to stop using it, that administrator has listed the entire Internet in the list zone. This happened with Osirusoft and ORBZ. In this case then yes, you will reject all email.

  1. You are using a common misspelling of a spamhaus DNSBL zone. In order to limit the bandwidth wasted by users querying for example spl.spamhaus.org when it should be sbl.spamhaus.org, the good folks at Spamhaus answer affirmatively to any query against any of these common misspellings. So if you think you are using spamhaus, check the spelling of the zone name carefully.