Developer reference
Messaging and email glossary.
Clear definitions for email authentication, messaging APIs, delivery, and AI agent tooling. Each entry explains the concept, its practical use, and relevant caveats.
- DKIMDomainKeys Identified MailDKIM (DomainKeys Identified Mail) is an email authentication standard. It lets a receiving mail server verify two things: that a message was genuinely sent by an authorised server for the sender's domain, and that the contents have not been changed since the message was signed.
- DMARCDomain-based Message Authentication, Reporting and ConformanceDMARC (Domain-based Message Authentication, Reporting and Conformance) is an email policy standard. It sits on top of SPF and DKIM and tells receiving mail servers exactly what to do when a message claiming to be from your domain fails authentication.
- SPFSender Policy FrameworkSPF authorises sending IPs for an envelope-sender or HELO domain. Receivers compare the connecting IP against that domain’s SPF record; SPF alone does not authenticate the visible From address.
- OTPOne-Time PasswordA one-time password (OTP) is a short, randomly-generated code that is valid only for a single use and a short period of time. Apps send OTPs by SMS, email or push notification to prove that a user owns the phone number or email address they signed up with.
- MCPModel Context ProtocolMCP (Model Context Protocol) is an open standard from Anthropic that lets AI agents like Claude safely use external tools. An MCP server exposes a set of well-defined tool functions; Claude can call those functions, receive structured results, and act on them.
- A2P 10DLCApplication-to-Person, 10-Digit Long CodeA2P 10DLC (Application-to-Person, 10-Digit Long Code) is the United States carrier registration system for any application that sends SMS messages from a standard 10-digit phone number. Carriers require every business sender to register their brand and the type of messaging they will do, so that legitimate traffic gets prioritised and spam gets filtered.
- BSPBusiness Solution ProviderA Business Solution Provider offers WhatsApp business-messaging services. Businesses can also integrate directly with Meta Cloud API; using a BSP is not the only route.
- WebhookWebhookA webhook is an HTTP POST request that one system sends to another whenever a particular event happens. Instead of the receiving system polling for changes, the sending system notifies it the moment something new occurs.