Email Glossary
Ever get stumped by email terminology? Browse this quick reference to decipher frequently used email terms, so you can turn a phrase like a pro in no time.
A
| Accreditation-based systems: Third-party whitelist programs that certify senders to convince ISPs that those using the systems are legitimate mailers who should not be blocked. Examples include: Bonded Sender from ReturnPath and Safelist from Habeas. |
| Authentication: Technical standards through which ISPs and other mail gateway administrators can establish the true identity of an email sender. Examples of proposed authentication standards include: SPF (PO Box, AOL), Sender-ID (Microsoft), DomainKeys (Yahoo), and DKIM (Cisco and Yahoo). |
B
| Blacklist, public: A list of IP addresses believed to send spam. Public blacklists are created and maintained by third parties; sometimes used by ISPs as another filtering mechanism to block email delivery. |
| Blacklist, private: A list of IP addresses believed to send spam, compiled by an ISP based on user complaints, mail sent to spam trap addresses, and "unknown user" rates. Each receiving ISP uses its own private blacklists to block email delivery. |
| Bounce: A message sent by a receiving system that "bounces back" to the originating server to alert the sender of the non-delivery. |
| Bulk mail folder: Folder within email clients to which questionable email is often directed. Also referred to as "Junk" or "Spam" folders in some email clients. |
| Blackhole: Term describing what happens to email that is blocked without a bounce response to the sender. |
C
| CAN-SPAM: Federal legislation governing unsolicited commercial email that went into effect on January 1, 2004. This law does not prohibit unsolicited commercial email, but it does regulate how it must be sent. Lawmakers intended to protect the end user and to make prosecution of spammers easier. |
| Challenge Response: Method of approving senders to specific email addresses that asks the email sender to answer a question proving he is a real person and not a "spam cannon" attempting to send email. Primarily used by Earthlink and selected client-side filters. |
| Commercial email: Marketing or sales oriented email that is sent in bulk. |
| Confirmed Opt-in: The process that double-checks the desire to be included on an email list after a primary registration occurs. This is typically executed via an email that requires the subscriber to click on a confirmation link, which also serves as a method of positively confirming the validity of the email address. |
| Content filters: Software filters that block email based on words, phrases, or header information within the email itself. The goal is to identify spam and filter to the Bulk or Junk mail folders, although this often results in "false positives". |
D
| Delivery monitoring: A process, usually using third party tools and techniques, to measure true delivery rates by campaign and ISP. Also tracks the amount and type of email tagged and/or blocked by server and client-side filters. |
| Dictionary attack: A type of spam program that bombards a mail server with millions of alphabetically generated email addresses in the hope that some addresses will be guessed correctly. |
| Domain: Internet addresses made up for words that correspond to the Internet Protocol (IP) numbers computers use to find each other. Domains always have two or more parts, separated by "dots". |
| DomainKeys: Email authentication system proposed by Yahoo! that checks an encrypted "key" embedded in each email sent against a list of public records to positively confirm the identity of the sender. |
| DNS: Domain Name System (DNS) translates domain names into an IP address to find the owner's site. |
E
| Email delivery rates: The percentage of email that gets delivered as intended; compiled from seedlist-based monitoring services and SMTP log files. |
| ECOA: Email Change of Address (ECOA) is a process that provides updated email addresses for data files based on consumer-provided, permission-based data. |
| Email append: Process that adds email addresses to postal files by merging files to match the postal address against email information in other files. |
| ESP: An Email Service Provider is a company that sends and manages email campaigns for other companies as a hosted service. |
F
| False-negative: When spam filtering devices fail to detect spam and allow it to be delivered. |
| False-positive: When spam filtering devices inaccurately identify legitimate email as spam and block delivery. |
G
| Greylisting: Process of routing email to a bulk folder if it is borderline spam, as determined by a receiving ISP. |
H
| Harvesting: Process that crawls the Internet to gather email addresses from Web sites and then uses them to create lists for spamming. |
| Header: The first part of an email message that contains controlling and meta-data such as the subject, origin and destination email addresses, the path an email takes, and its priority. May be used to filter, track spammers or uncover information about delivery rates. |
I
| IP addresses: Internet Protocol addresses. The numeric identification number that refers to a specific machine on the Internet. |
| Internet Service Provider (ISP): Company that provides access to the Internet through connectivity services. Examples include AOL, Comcast, Earthlink, and Verizon. |
L
| List hygiene: Process of cleaning email files to ensure all addresses are accurate, current, opt-in and deliverable. |
M
| Machine-learning filters: Filters run by machines that determine whether to block email based on algorithms that point to whether the message is likely spam. |
O
| Open relay: SMTP email server that allows the third-party relay of email messages through the SMTP "port" on a server (port 25). While this feature of SMTP servers has legitimate uses, spammers have learned how to locate unprotected servers and use them to send spam. |
| Open proxy: Software that exists on a server that allows the third-party relay of e-mail messages through ports other than port 25. |
| Opt-in: Process of agreeing to receive email from a business source. Confirmed opt-in refers to a double-check procedure in which a decision to be included on a mailing list is confirmed. |
| Opt-out: Process of declining to receive email from a business source or unsubscribing if the recipient is already on a mailing list. |
P
| Phishing: (Pronounced 'fishing') The act of forging emails that claim to be from a legitimate sender, such as a bank, for the purpose of identity theft or robbery. Phishing emails usually link to a replica of a legitimate web page that tries to trick users into submitting personal or financial information or passwords. |
| Postmaster: The person who manages mail servers at an organization. Usually the one to contact at a particular server/site to get help, information, or to log complaints. |
R
| Rich media: A category of web technologies that utilize streaming video, audio and other static or animated files to create an advanced media experience for viewing content. |
S
| Seed list: A list of email addresses that should be included in every email event to monitor delivery across email platforms. Can be executed in-house or through a third-party vendor. |
| Sender-ID: An authentication standard proposed by Microsoft, that compares an email sender's "From" address to the IP address authorized to send email from that domain. |
| SPF: SPF (Sender Policy Framework) compares an email sender's actual IP address to a list of IP addresses authorized to send mail from that domain. This list is published in the domain's DNS record. |
| SMTP: Simple Mail Transfer Protocol, a server-to-server protocol used to transfer email between computers. |
| SMTP log file: A file showing all conversations back and forth between servers during the email send and receive process. Used to uncover problems with various deliverability factors such as unknown user rates. |
| Spam: Widely-used slang reference to unsolicited commercial email messages. Named after the Monty Python "Spam" song. |
| Spam filter: Systems that watch for spam and block it before it can hit the inbox. Spam filters can be complaint or content based. |
| Spam-trap address: An email address that is set up specifically to catch people who are harvesting addresses or using directory attacks to send unsolicited email. Used by Brightmail, ISPs and many in the anti-spam community. |
| Spoofing: Forged email addresses that hide the origin of a spam or virus message. Used to trick people into opening an email because they believe it has come from a legitimate source. |
| Suppression list: A list of email addresses kept by a single organization that should not be mailed to any longer. Usually owners of the addresses on the list have specifically requested inclusion. Required by CAN-SPAM. |
U
| Unknown User: Bounce error code generated by an ISP when an email address is not registered in its system. |
V
| Verified opt-in: Formerly known as double opt-in. Requires secondary confirmation from an email address to confirm intended registration to receive email. |
W - Z
| Whitelist: A list of trusted IP addresses and domains that allows all mail from these addresses to be delivered, bypassing spam filters. |
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