Email authentication

Email authentication is a set of three checks that prove a message really came from the domain it claims. Without them, anyone can send mail that appears to be from your address.

MailMoose sets all three up when you connect a domain, and shows you the result on every message you receive.

The three checks

1. SPF lists which services are allowed to send mail as your domain. A receiver looks up your SPF record and checks whether the sending server is on the list.
2. DKIM adds a cryptographic signature to every message you send. A receiver verifies it against a key published in your DNS, which proves the message came from you and was not altered on the way.
3. DMARC ties the two together and tells receivers what to do when a message fails. It also lets you ask for reports about mail sent in your name.

Why they matter

1. Your mail reaches inboxes. Providers treat unauthenticated mail as suspicious. Gmail and Outlook now require authentication for most senders.
2. Nobody can impersonate you. Without DMARC, a scammer can send invoices that appear to come from your domain, to your own customers.
3. You can see when others are impersonated. Every message you receive shows whether it passed.

Reading the badge on a message

Each message in your inbox shows the outcome of these checks.

A failed check does not always mean fraud. Forwarded mail sometimes breaks SPF legitimately. But an unexpected invoice from a supplier that fails DMARC deserves a phone call before you pay anything.

Tightening DMARC over time

MailMoose starts your DMARC policy permissive, which means receivers are told to accept mail that fails and simply report it. That is deliberate. A strict policy on a new domain can silently send your own mail to spam while records settle.

Once you have run for a few weeks without problems, you can tighten the policy at your registrar:

1. p=none reports failures but delivers everything. This is where you start.
2. p=quarantine sends failing mail to spam.
3. p=reject refuses failing mail outright. This is the strongest setting.

Move one step at a time and watch for problems before going further.