A common problem faced with today's antispam solutions is the lost of important mails. Some of them might mistakenly categorise a valid mail as spam (technically known as a false positive) due to poor spam-detection techniques (algorithms).

However a lot of valid mails could also be rejected because the mails originate from a server that is blacklisted in DNS Blacklist databases (DNSBL). Administrators using such solution are all too aware of complaints from their users failing to receive valid mails because the party that they are communicating with is correctly or incorrectly blacklisted by DNSBL. In such this kind of situations, the users will not know that they are missing any mails because the mails will not even appear under their spam folder. Instead the mails will be refused by the antispam solution. Normally, the problem is only brought to the users' attention, when their business partners report of receiving a bounced back mail indicating such problems.

Typically the duration it takes to solve such a problem can be rather long. The email administrator would put the blame on the sending party and would normally insist that they take the necessary measure to have their IP removed from the DNSBL. The sending party might lack the technical nous and struggle to under the steps in removing their IP effectively. Therefore removal from such database can take from a few hours to over day.

At the end of the day, users are not interested in why the sender's server was blacklisted. They only care about receiving their business-related mail from that source.

AntispamNow! does not make use of DNSBL.

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