Almost
every mail server and certain firewalls use an IP address blacklist to
determine whether to receive emails, mark these as ‘Junk’, or to drop traffic. To
tackle these things, several individuals started to keep lists that record which
party creates spam and malicious software. Keep reading to know more about IP
blacklists.
Issues With IP Blacklists
The
major issue with the blacklists is that these block traffic at an inappropriate
time. Some blacklists deliberately do this, thereby forcing those who hold big
blocks of IPv4 addresses to act to keep spam from getting to their customers. A device sometimes gets blacklisted
due to spam, but it may be patched and that spam stopped afterward.
Several
blacklists come with an ‘aging’ time, where an internet protocol address would
be excluded from the blacklist if no more issues are reported or noticed over time.
If it is re-reported, the address being aged out might just take longer the
next time it occurs.
An IP address for sale may already
be blacklisted. This means you have to do your due diligence when looking to purchase
the address. It is possible to list and delist Internet Protocol Version 4
addresses at any given time, so blacklist verification from 14 days before may not
have any connection with the present one.
IP Address Blacklist Removal
Each
maintainer of an IP blacklist has a unique mechanism to have addresses delisted,
which tends to require some evidence that the actual reason for its listing is
eliminated. For many lists of Spam and Open-Relay Blocking System (SORBS), you
should ask for a retest with the following steps.
·
·
In
the event of the test passing, SORBS would flag the IP address that should be delisted.
If you lack access to the system, or the device has no web browser, then you
could try opening a SORBS support ticket.
Almost every blacklist operator knows that an unrouted IP address is not the origin of spam. This means making your network offline, like you would do to prepare for a sale, gives SORBS a fair reason to reconsider retesting your machine. Likewise, the evidence of the time a block of IPv4 addresses was transferred, tends to be acceptable documentation.