Address / Email Harvester
A robot that browses web pages for anything that resembles a valid email address that can be used to spam.


Alias
An alternate name given to a mailbox.


Blacklists or Blocked List
Allows users to designate a domain or IP address and email addresses from which no mail will be accepted.


Catch Rate
The percentage of spam mail caught by a spam solution. It measures the efficiency of the solution at identifying and stopping spam.


Content filtering
Scans plain text for key phrases and the percent of HTML, images and other indications that the message is spam.


Denial of Service (DoS)
A type of attack against a mail server which cripples it - meaning that legitimate users of the mail server are denied access to the service it provides because the system is under attack by an unauthorized or malicious person or program.


Dictionary Attack
A "Dictionary" or NDR (Non-Delivery Report) attack is a sequence of Spam messages that attempts delivery to every possible recipient name on a server. Some servers attempt to protect against dictionary attacks by accepting messages for all recipients rather than rejecting invalid recipients and letting a Spam sender know which accounts are valid. Unfortunately, this often leads to very high server loads due to all the extra processing involved with handling hundreds or thousands of unwanted requests.


Dictionary Attack Software
Software that automatically generates likely email addresses. The program combines letters and numbers in an attempt to find active email addresses.


Domain Name System Black List or Domain Name System Black hole List (DNSBL)
An online database of email spam sites which can be used for email spam filtering, either on a personal basis or on an entire domain. Problem sites are added to DNSBLs almost instantly when spam is identified, and are removed once the problem is dealt with. DNSBLs typically come in two flavors - Exploit-Targeting Blacklists (that is, list of open relays, open proxies, etc) and Spammer-Targeting Blacklists (Spamhaus SBL and Spamcop are typical spammer-targeting lists).


False Negative
A false negative is an email that is spam, but which was not recognized by an anti-spam solution and was released to your inbox as legitimate email.


False Positive
A false positive is a legitimate email, but which was recognized by an anti-spam solution wrongly as spam email and withheld from your inbox.


Filter
An email feature that allows users to either kill email or channel it to a specific folder.


Filter Scripting
Uses advanced filtering logic methods to block many or all spam tactics.


Fingerprinting
Identifies that similar, yet not identical, messages are part of the same spam broadcast.  Also, a technology that scans email attachments in search of forbidden file formats (such as *.exe or *.vbs) in order to stop forbidden files being concealed with modified file extensions.


Headers
The portion at the beginning (or top) of an email that contains the sender’s name, date
the message was sent, recipients’ names, title, routing details, message priority, and other information.


Internet Message Access Protocol version 4 (IMAP4)
A method of accessing mail or bulletin board messages that are kept on a mail server. An email client can access the remote message stores, and manipulate them (sort them into folders) as if they were local. Typically this protocol differs from the Post Office Protocol version 3 (POP3) by the fact that messages are copied to the email client computer, but also remain on the server.


Lightweight Directory Access Protocol (LDAP)
A client/server protocol for accessing information in network directories such as Novell
Directory Services (NDS), Microsoft Active Directory, or directories that follow the X.500
standard.


Open Proxy
A proxy that will allow other machines to use it to make connections to services on their
behalf, whether they would normally have permission to access the service or not.


NDR (Non-Delivery Report) Attack
See Dictionary Attack.


Open Relay
An email server processing mail where sender and receiver are not local users. Such servers are often open to attack, and are sometimes hijacked and used to send large amounts of spam.


Phishing
A high-tech scam that uses spam to deceive consumers into disclosing their credit card
numbers, bank account information, Social Security numbers, passwords, and other sensitive information.


Post Office Protocol version 3 (POP3)
The most common protocol for authentication and transmission of email messages over the internet. This protocol is used by an email client to retrieve email from the mail server (and typically the mail is MOVED from the mail server to the client’s machine).


Quarantine
To isolate files suspected of containing a threat such as a virus, so that it can not be opened.


Quarantine Report
A report of an account’s quarantined email that is sent to a user’s inbox at regular
intervals. This report is only generated when a user’s account has email that has been
identified either as spam or containing a virus and which has accordingly been withheld from the user’s inbox.


Realtime Black List (RBL)
An online database of email spam sites that may be used for email spam filtering, either on a personal basis or used by an entire site. Problem sites are added to the RBL almost instantly when spam becomes a problem, and are removed again quickly once the problem is dealt with.


Realtime Whitelist Servers
A realtime whitelist server is a DNS list of Domains and/or IP addresses for companies
whose mailing practices are vouched for by the organization who compiled the list. Enabling a realtime whitelist server means that all incoming mail you receive will have
its sender information compared to that online list, and if a match is found, the email will be processed as legitimate mail (unless a virus is detected).


Reverse DNS
A mechanism that allows the sender’s domain to be contacted for verification.


SMTP (Simple Mail Transport Protocol)
A protocol for sending (or relaying) email to a server.


Spam
Unsolicited, unwanted, bulk, commercial email.


Trusted List/Trusted Sender List
Trusted Lists allows you to designate a source or IP address from which all mail will be accepted, even if individual messages earn high spam ratings. A  Trusted Sender List is a user’s list of email addresses from whom the user always wants to receive mail. This list usually overrides a system’s spam checks so that false positive results can be avoided.


URL (Universal or Uniform Resource Locator)
This is an internet address used by web browsers for a specific computer or a document
(resource).


Whitelists
See Trusted List

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