- SPF
- Sender Policy Framework — a DNS record listing which servers may send email for your domain. Receivers check it to detect forged senders.
- DKIM
- DomainKeys Identified Mail — a cryptographic signature added to outgoing mail, proving the message wasn't altered and genuinely comes from the signing domain.
- DMARC
- A policy layered on SPF and DKIM that tells receivers what to do with mail that fails authentication — monitor, quarantine, or reject — and sends you reports about it.
- BIMI
- Brand Indicators for Message Identification — displays your verified logo next to your emails in supporting inboxes. Requires DMARC at enforcement.
- VMC
- Verified Mark Certificate — the certificate that proves you own your logo (usually via trademark), required for BIMI display in Gmail and Apple Mail.
- MTA
- Mail Transfer Agent — the server software that actually sends and routes email. PowerMTA, Haraka and Postfix are MTAs.
- VMTA
- Virtual MTA — an isolated sending identity (IP + domain pairing) inside an MTA like PowerMTA, used to separate mail streams and protect reputation.
- SMTP relay
- A service that accepts your application's mail and delivers it onward — the standard way apps send transactional email without running full infrastructure.
- White-label platform
- A complete product deployed under another company's brand — for email, a full sending platform your customers see as yours.
- On-premise deployment
- Running software inside your own data center or infrastructure rather than a vendor's cloud — full control over data, compliance and residency.
- IP warm-up
- The practice of gradually increasing sending volume on a new IP address so mailbox providers can build trust in it before full-scale sending.
- Feedback loop (FBL)
- A mechanism where mailbox providers report spam complaints back to the sender, so complaining recipients can be removed promptly.
- MX record
- The DNS record that tells the world which servers receive email for your domain.
- ARC
- Authenticated Received Chain — preserves authentication results when mail is forwarded through intermediaries like mailing lists.
- MTA-STS
- A standard that lets domains require encrypted (TLS) connections for inbound mail, preventing downgrade attacks.
- TLS-RPT
- TLS Reporting — companion to MTA-STS; senders report back on TLS delivery successes and failures to your domain.
- Sender reputation
- The trust score mailbox providers assign to your sending IPs and domain, built from complaint rates, engagement, volume patterns and authentication.
- p=none / quarantine / reject
- The three DMARC policy levels: monitor only, deliver-to-spam on failure, and refuse delivery on failure.