Email Authentication

Email authentication is the collection of standards that let a receiving server verify a message genuinely originated from the domain it claims to be from, and was not forged or altered. The three pillars are SPF, DKIM, and DMARC. Together they answer the question every mailbox provider asks: is this sender who they say they are?

Why it matters for outbound

Authentication is the price of entry for cold outbound. Mailbox providers now expect senders to authenticate, and unauthenticated mail is heavily filtered or rejected. Beyond passing the gate, correct authentication builds the sender reputation and domain reputation that drive long-term inbox placement. Skipping it is the single most common reason a technically sound campaign lands in spam.

Outword verifies the full authentication stack on every sending domain before a single message goes out, because everything downstream depends on it.

How it works

• SPF declares which servers may send for the domain.
• DKIM cryptographically signs each message to prove it is genuine and unaltered.
• DMARC ties the two together, sets a failure policy, and reports on abuse.

Each is published as a DNS record. They are complementary, not redundant: SPF checks the path, DKIM checks the content, and DMARC enforces alignment between them. Our deliverability and inbox placement service configures and monitors all three.