A working vocabulary for business email. Definitions are deliberately brief; follow the links for the mechanics.
- Domain
- A name you register, such as yourcompany.co.zm, that identifies your organisation on the internet. Email addresses, websites and DNS records all hang off it. More
- Nameserver
- A server that answers DNS queries for a domain. The registrar records which nameservers are authoritative; ontechmail's are ns1 and ns2.ontech.co.zm. More
- DNS
- The Domain Name System, the distributed directory that maps names to addresses and holds the records (A, MX, TXT and others) that tell the internet where a domain's services live. More
- A record
- A DNS record mapping a hostname to an IPv4 address; AAAA does the same for IPv6. Points a website at its host. More
- CNAME
- A DNS record that makes one hostname an alias of another. Cannot be used on the bare domain alongside MX records. More
- TXT record
- A free-text DNS record. SPF, DKIM and DMARC policies are all published as TXT records. More
- TTL
- Time to live: how long, in seconds, resolvers may cache a DNS answer. Lower it before planned changes so they take effect sooner. More
- MX record
- Mail exchanger record: names the server that receives email for a domain, with a priority. Changing it changes your email provider. More
- SPF
- Sender Policy Framework: a TXT record listing the servers allowed to send mail for a domain. Checked against the connecting server's IP address. More
- DKIM
- DomainKeys Identified Mail: a signature added to outgoing mail with a private key, verified by receivers using a public key published in DNS. More
- DMARC
- A policy record that requires SPF or DKIM to align with the visible From domain, tells receivers what to do with failures, and delivers reports. More
- Alignment
- In DMARC, the requirement that the domain which passed SPF or DKIM matches the domain in the From header. More
- Selector
- The label in a DKIM signature that tells receivers which DNS record holds the public key, allowing several keys per domain. More
- SMTP
- Simple Mail Transfer Protocol: how mail is submitted by clients (ports 465 and 587) and relayed between servers (port 25). More
- SMTP submission
- Authenticated SMTP on port 465 or 587 through which a user or application hands outgoing mail to their provider. More
- IMAP
- Internet Message Access Protocol: lets clients read and manage a mailbox that stays on the server, keeping every device in sync. ontechmail: port 993. More
- POP3
- Post Office Protocol: downloads mail to a single device, usually removing it from the server. ontechmail offers it on port 995 for tools that require it. More
- TLS
- Transport Layer Security: the encryption used for HTTPS, IMAP on 993, POP3 on 995 and SMTP on 465/587. STARTTLS upgrades a plain connection to TLS. More
- Mail server
- Software that receives, stores, or sends email. An email host runs several: an inbound receiver, an IMAP server, a submission server and an outbound worker. More
- Email hosting
- The service of running the mail servers for a domain: receiving, storing and sending its mail, and providing access through webmail and IMAP. More
- Business email
- Email on a domain the organisation owns, hosted by a provider, with addresses that belong to the organisation rather than to individuals. More
- Catch-all mailbox
- A mailbox that receives mail sent to any address on the domain that has no mailbox of its own. More
- Webmail
- A mail client that runs in the browser, reading the same server-side mailbox as IMAP clients. More
- Two-factor authentication (2FA)
- A sign-in step requiring a second proof, such as a time-based code from an authenticator app, in addition to the password. More
- Open relay
- A mail server that forwards mail from anyone to anyone; a spam source. ontechmail's receiver only accepts mail for domains it hosts. More
- Self-hosted email
- Running the mail platform on servers your organisation controls rather than on a provider's infrastructure. More
- Air-gapped
- A system with no connection to the public internet, used for internal-only mail on sensitive networks. More
- Data sovereignty
- The principle that data is subject to the laws of the country where it is stored and processed; for email, knowing which jurisdiction holds your mailboxes and keys. More
- Data residency
- Where data is physically stored. A fact about location, distinct from legal compliance. More
- Audit log
- A record of administrative actions with actor, target and time, used as evidence for security reviews and regulators. More