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DNSBL Filter Problems [message #1729] Tue, 05 June 2007 11:33
freddyKrueger
Messages: 20
Registered: October 2006
Junior Member
Hello,
the DNSBL Filter causes lots of problems with mobile users or travellers.

Problem:
Users who were able to send mails before are suddenly blocked, because they're travelling and getting a dynamic IP, that had been used by spammers before.

Solution:
It would be better if one could configure a score for this filter the same way it is in the spamassassin integrated DNSRBL filter. The AWL score off those users would prevent those mails from beeing blocked.

The way it works now makes the filter unusable because it's blocking some off the most important mails. ( From travelling people )
Re: DNSBL Filter Problems [message #1730 is a reply to message #1729] Tue, 05 June 2007 11:46 Go to previous message
support
Messages: 919
Registered: April 2004
Senior Member
This issue can easily be resolved by having users connecting from outside
use SMTP AUTH.

> the DNSBL Filter causes lots of problems with mobile users or
> travellers.
>
> Problem:
> Users who were able to send mails before are suddenly blocked,
> because they're travelling and getting a dynamic IP, that had
> been used by spammers before.
>
> Solution:
> It would be better if one could configure a score for this
> filter the same way it is in the spamassassin integrated DNSRBL
> filter. The AWL score off those users would prevent those mails
> from beeing blocked.
>
> The way it works now makes the filter unusable because it's
> blocking some off the most important mails. ( From travelling
> people )



Customer Support
Byteplant GmbH
Re: DNSBL Filter Problems [message #1731 is a reply to message #1730] Tue, 05 June 2007 14:39 Go to previous message
freddyKrueger
Messages: 20
Registered: October 2006
Junior Member
Is SMTP Auth not only for accounts from our domains ?
We have this problem with mails from customers, which are comming from foreign domains, so i think smtp auth won't help.
Re: DNSBL Filter Problems [message #1732 is a reply to message #1731] Tue, 05 June 2007 16:46 Go to previous message
support
Messages: 919
Registered: April 2004
Senior Member
> Is SMTP Auth not only for accounts from our domains ?
> We have this problem with mails from customers, which are
> comming from foreign domains, so i think smtp auth won't help.

SMTP AUTH should be established generally for all mail delivered to your mail server for relaying to prevent your server from being used as an open relay.



Customer Support
Byteplant GmbH
Re: DNSBL Filter Problems [message #1733 is a reply to message #1732] Wed, 06 June 2007 09:39 Go to previous message
freddyKrueger
Messages: 20
Registered: October 2006
Junior Member
SMTP Auth is on, but doesn't help.

Example:
Customer or partner from Domain xyz.de is sending mails from inside their company building to our domain.
He's getting an average score of -2.1.
Customer starts traveling. He's got a meeting with one of our employes in some foreign country. While he's travelling he tries to send a mail. ( I will be later, the meeting is at another place, please do ... before we meet )
This mail is rejected by the DNSBL Filter because he's got some suspicous dynamic IP.

So we have to turn off this filter, because it's preventing very time critical mails from arriving.
Re: DNSBL Filter Problems [message #1734 is a reply to message #1733] Tue, 12 June 2007 11:20 Go to previous message
support
Messages: 919
Registered: April 2004
Senior Member
> Customer or partner from Domain xyz.de is sending mails from
> inside their company building to our domain.
> He's getting an average score of -2.1.
> Customer starts traveling. He's got a meeting with one of our
> employes in some foreign country. While he's travelling he
> tries to send a mail. ( I will be later, the meeting is at
> another place, please do ... before we meet )
> This mail is rejected by the DNSBL Filter because he's got some
> suspicous dynamic IP.

Be very careful when you choose the DNSBL zones queried by the filter. The default setting does not query zones that include dynamic IP addresses.



Customer Support
Byteplant GmbH
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