Authenticated Received Chain
A mechanism preserving email authentication information across forwarding. ARC helps receivers evaluate intermediaries but does not replace SPF, DKIM or DMARC.
Definition and sourcesKNOWLEDGE / FROM A TO Z
Glossary
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Terms 35 / 685
Clear filtersAutoresponder
A mechanism automatically replying to messages, such as during absence. Frequency and recipient limits help prevent reply loops and unnecessary disclosure.
Definition and sourcesBandwidth
A connection's capacity to transfer data over time. It differs from latency; a high-capacity link can still have slow response times.
Definition and sourcesBCC email field
The blind-carbon-copy email field, labelled UDW in Polish. It limits recipient disclosure but neither encrypts messages nor replaces a proper bulk-email system.
Definition and sourcesBIMI
A specification enabling brand indicators beside authenticated email. Support depends on the mailbox provider, DMARC policy and mark-verification requirements.
Definition and sourcesBing
Microsoft's web search engine. It has its own indexing and guidelines; Google visibility does not guarantee equivalent presence in Bing.
Definition and sourcesCC email field
The email carbon-copy field, labelled DW in Polish interfaces. Addresses are normally visible to other recipients; it does not hide a contact list.
Definition and sourcesDarknet
An overlay network requiring special software or access configuration. It is not synonymous with all unindexed content and has both lawful and unlawful uses.
Definition and sourcesDMARC
A domain policy evaluating SPF or DKIM alignment with the sender domain and requesting handling. The p=none policy monitors rather than requests rejection.
Definition and sourcesDomainKeys Identified Mail
A mechanism signing selected email elements with a domain key. Receivers verify signatures through DNS; DKIM does not encrypt message content.
Definition and sourcesE-commerce
Commerce where goods or services are ordered electronically, usually online. Payment and delivery need not occur online. E-commerce includes both business transactions and consumer sales.
Definition and sourcesEmail alias
An additional address delivering mail to an existing mailbox. It usually has no separate password or storage; sending behaviour depends on the provider.
Definition and sourcesHTTP 401
An HTTP response indicating missing valid authentication. The server should provide a WWW-Authenticate challenge; it differs from a 403 permission refusal.
Definition and sourcesHTTP 408
An HTTP status for the server timing out while waiting for the client's request. It differs from 504, involving a gateway waiting for another server.
Definition and sourcesHTTP 503
An HTTP status indicating temporary unavailability, such as overload or maintenance. Retry-After can suggest when the client should retry.
Definition and sourcesHTTP/2
An HTTP version with binary framing and multiple streams per connection. It can reduce communication overhead but does not solve application-performance problems.
Definition and sourcesHTTP/3
An HTTP version using QUIC rather than TCP. It changes transport and connection-establishment behaviour; benefits depend on network, client and infrastructure.
Definition and sourcesIntranet
An organisation's internal network or services for authorised users. Internal does not automatically mean secure; authentication and segmentation still matter.
Definition and sourcesIP (Internet Protocol)
Protocols for addressing and forwarding packets between networks, notably IPv4 and IPv6. IP itself guarantees neither delivery nor ordering nor encryption.
Definition and sourcesIP address
A network interface address used to route IP packets. It can change or be shared; an address alone does not uniquely identify a person.
Definition and sourcesIPv4 address
A 32-bit IP address, usually written as four dot-separated numbers. Limited public IPv4 availability encourages address sharing through NAT.
Definition and sourcesIPv6 address
A 128-bit IP address written in hexadecimal. IPv6 provides a much larger address space, while still requiring firewalls and access controls.
Definition and sourcesMTA Strict Transport Security
A policy allowing domains to require secure SMTP transport to designated servers. It needs valid certificates and configuration and is not end-to-end email encryption.
Definition and sourcesNetiquette
Guidelines for considerate online communication, respecting context and privacy. Historical guidance should be interpreted for modern channels rather than treated as immutable internet law.
Definition and sources