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Context filtering is an anti-spam / mail policy method that does not deal with the contents of the mail but rather uses the context of the SMTP connection to decide whether a mail will be accepted or not.
This method usually prevents reception of an e-mail in the first place; thus, common anti-spam features like quarantine, redirect or delete can not be applied. This method also distorts statistics of anti-spam programs because it is usually unknown how many mails (Spam or otherwise) would have been received through a certain connection.
Filtering by context includes methods like DNSBL lookups, domain or IP blacklists, etc. This method has an extremely low rate of false positives and false negatives.
On the plus side, this method is usually saving bandwidth and server utilization.
The most common context filter is DNSBL filtering. The efficiency of this method depends on the blacklist used.
For high volume mail sites, it is recommended to set up local copies of the DNSBLs of your choice and fill them through DNS zone transfers. This reduces the permanent traffic through external DNS lookups. Some DNSBLs also allow only a certain amount of queries by day for every IP address to keep their expenses on bandwidth low.
Contextfiltering is an anti-spam / mail policy method that does not deal with the contents of the mail but rather uses the context of the SMTP connection...
Collaborative filtering (CF) is a technique used by recommender systems. Collaborative filtering has two senses, a narrow one and a more general one. In...
filter. The process of filtering out the most 'unique' elements can also be repeated multiple times by changing the hash function in each filtering step...
Kalman filtering is a concept much applied in time series analysis used for topics such as signal processing and econometrics. Kalman filtering is also...
high magnitude, then a median filter may be more appropriate. The context here is the formulation of the nonlinear filtering problem seen through the lens...
sinc-in-time is often assumed, or context hopefully can infer the correct domain. Sinc-in-time is an ideal filter that removes all frequency components...
component of ensemble forecasting. EnKF is related to the particle filter (in this context, a particle is the same thing as an ensemble member) but the EnKF...
for expediting operations such as filtering. Digital filters may be more expensive than an equivalent analog filter due to their increased complexity...
systems usually make use of either or both collaborative filtering and content-based filtering (also known as the personality-based approach), as well...
overwrite them regardless of their context. More advanced wordfilters make some exceptions for context (such as filtering "butt" but not "butter"), and the...
In the context of network routing, route filtering is the process by which certain routes are not considered for inclusion in the local route database...
doing spam filtering, with roots in the 1990s. Bayesian algorithms were used for email filtering as early as 1996. Although naive Bayesian filters did not...
typically use collaborative filtering approaches or a combination of the collaborative filtering and content-based filtering approaches, although content-based...
system. Ports can be "closed" (in this context, filtered) through the use of a firewall. The firewall will filter incoming packets, only letting through...
policies. Browser based filters Browser based content filtering solution is the most lightweight solution to do the content filtering, and is implemented...
multirate filtering is that the signal should be filtered before decimation, otherwise aliasing and frequency folding would occur. Multirate filter design...
Alarm filtering, in the context of IT network management, is the method by which an alarm system reports the origin of a system failure, rather than a...
same transfer function of the filters described in this article. Analogue filters are most often used in wave filtering applications, that is, where it...
that he adopted to avoid it being referred to as the “Uhlmann filter.” Many filtering and control methods represent estimates of the state of a system...
server and filtering software never sees any communications with the web servers from which content really originated. To counter this, filtering software...
Generalized filtering is a generic Bayesian filtering scheme for nonlinear state-space models. It is based on a variational principle of least action...
resonator. The term "filtering" indicates that the desirable structural features of the original source pass through the filter, while the undesirable...
may include filtering out such content. LLM-generated content can pose a problem if the content is similar to human text (making filtering difficult) but...
Particle filters, or sequential Monte Carlo methods, are a set of Monte Carlo algorithms used to find approximate solutions for filtering problems for...
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