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DNSBL Questions [message #2255] Mon, 02 August 2010 17:15 Go to next message
WaveJam
Messages: 22
Registered: June 2005
Junior Member
Hi there,

Could you please help me understand the following about a DNSBL filter?

1. How many zones can be listed in a DNSBL filter? Does this greatly impact performance? I'm a small business so I don't have high volume email. Hoping that I can list more zones to get better results.

2. Do all the zones get checked for each email that passes through? If not, can it be?

3. I'm torn between accept/delete and reject/delete for the DNSBL. Is there a better way to go? I'm sure its a preference thing and I wanted to hear other peoples preferences...

Thanks.
Re: DNSBL Questions [message #2263 is a reply to message #2255] Tue, 03 August 2010 09:14 Go to previous messageGo to next message
support
Messages: 905
Registered: April 2004
Senior Member
1. How many zones can be listed in a DNSBL filter? Does this greatly impact performance? I'm a small business so I don't have high volume email. Hoping that I can list more zones to get better results.

Yes, you can add additional zones as you like in the DNSBL filter, as the performance impact is minimal.

2. Do all the zones get checked for each email that passes through? If not, can it be?

Yes, all zones configured in the DNSBL filter are checked.

3. I'm torn between accept/delete and reject/delete for the DNSBL. Is there a better way to go? I'm sure its a preference thing and I wanted to hear other peoples preferences...

If you decide to delete a blacklisted email (which is what we recommend), you should choose reject/delete as policy to give the sender a feedback that his email has not reached its destination. Accept/delete does only make sense if CleanMail sits behind e.g. an Anti-Virus firewall that has already accepted an incoming spam mail and therefore a reject policy would be inappropriate.


Customer Support
Byteplant GmbH

[Updated on: Tue, 03 August 2010 09:16]

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Re: DNSBL Questions [message #2264 is a reply to message #2263] Tue, 03 August 2010 12:43 Go to previous messageGo to next message
WaveJam
Messages: 22
Registered: June 2005
Junior Member
Thank-you for the responses. One thing that I forgot to ask is, if I whitelist a specific email address, does that email/connection bypass the DNSBL check?

One of the domains that frequently used by spammers, also has a legit email or two coming from it. So I'm hoping to whitelist the specific addresses and let the DNSBL kill the others.
Re: DNSBL Questions [message #2265 is a reply to message #2264] Tue, 03 August 2010 12:48 Go to previous message
support
Messages: 905
Registered: April 2004
Senior Member
Thank-you for the responses. One thing that I forgot to ask is, if I whitelist a specific email address, does that email/connection bypass the DNSBL check?

Yes, the whitelist normally bypasses other filters.
For security reasons, anti virus filters and the attachment blocker by default ignore whitelisting. You can change this behaviour by removing the check mark from the Ignore Whitelist setting.


Customer Support
Byteplant GmbH
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