Email Setup Guide
Business Email Setup: SPF, DKIM and DMARC Explained
A practical explanation of the DNS and authentication work behind professional business email, including SPF, DKIM and DMARC.
01
Why business email setup matters
A professional mailbox is only one part of a reliable sending setup. The domain also needs the right authentication records so receiving systems can check that legitimate services are authorised to send mail for the domain.
SPF, DKIM and DMARC are the core authentication records commonly involved in this setup. UK National Cyber Security Centre guidance recommends implementing these controls and monitoring them as part of email anti-spoofing.
02
SPF: which senders are authorised
SPF is a DNS record that lists the IP addresses or services authorised to send email for a domain. The exact record depends on every legitimate sending service used by the business.
Do not copy an SPF example blindly. The authorised services need to be based on the systems that actually send mail for the domain.
03
DKIM: proving the message was signed
DKIM adds a cryptographic signature to outgoing mail so receiving systems can verify that the message was signed by an authorised domain. The exact selector and DNS record come from the email or sending provider.
04
DMARC: telling receivers what to do
DMARC tells receiving systems how to handle messages that do not pass authentication checks and can provide reporting on authentication results. A sensible rollout starts by monitoring the domain, fixing legitimate senders, and then tightening the policy when the business is confident the configuration is correct.
05
DNS verification before outreach
Authentication records need to exist in the public DNS and then propagate. The exact steps depend on the DNS provider and the email platform. Arcturus provides one-time Email Setup for this technical foundation, including SPF, DKIM, DMARC and DNS verification.
Email Setup is separate from the managed Email Outreach service so the technical configuration and campaign management remain clearly scoped.
06
What setup does not guarantee
Correct authentication is important, but it does not guarantee that every email reaches the inbox. Sender reputation, list quality, sending behaviour, message content and recipient systems also affect delivery.