The Simple Guide to Keeping Your Business Emails Safe
For many business owners, email security can feel like a confusing mix of acronyms and technical jargon. Yet three important technologies, SPF, DKIM and DMARC, work quietly in the background to protect your business from email fraud, phishing attacks and impersonation.
This guide explains what they are, why they matter, and how they help protect your organisation.
Why Email Security Matters
Imagine receiving an email that appears to come from your bank, your supplier, or even your own company. The logo looks right, the sender’s address appears genuine, and the message asks you to make a payment or share sensitive information.
Unfortunately, cybercriminals do this every day.
This type of attack is known as email spoofing, where someone pretends to be a trusted sender. Without proper protection, criminals can send emails that look as though they came directly from your business.
SPF, DKIM and DMARC are designed to stop this from happening. They help receiving email systems verify that messages genuinely come from your domain and haven’t been tampered with during delivery. Unfortunately this doesn’t help if the criminals purchase a different domain close in name to the one they are spoofing, so you still need to be on your guard.
What Is SPF?
Sender Policy Framework
Think of SPF as the guest list for your company email.
When someone sends an email from your domain (for example, yourcompany.co.uk), the receiving email server checks your SPF record to see whether the sending server is authorised.
A Simple Example
Imagine you’re hosting a private event.
You provide security with a list of approved guests. When someone arrives, security simply checks whether their name is on the list.
- If they’re on the list, they’re allowed in.
- If they’re not on the list, they’re turned away.
SPF works in exactly the same way.
It tells the internet which servers are permitted to send emails on behalf of your business. If an unauthorised server tries to send mail pretending to be you, SPF helps identify that message as suspicious.
Benefits of SPF
- Reduces email spoofing.
- Improves email deliverability.
- Helps prevent your domain being abused by scammers.
- Provides the first layer of email authentication.
A good example of when the SPF comes into play is when companies use bulk marketing platforms like Mailchimp. The SPF is adjusted to enable them to send from their systems using your domain.
Important Note
SPF on its own is not enough. Criminals have found ways around SPF, which is why DKIM and DMARC are also required.
What Is DKIM?
DomainKeys Identified Mail
If SPF is the guest list, DKIM is the digital signature.
Whenever your email system sends a message, it adds a unique cryptographic signature. The receiving mail server can then verify that signature against information published in your DNS records.
A Simple Example
Imagine signing an important contract.
Your signature proves that the document came from you.
Now imagine someone changes part of the contract after you’ve signed it. The signature would no longer match the contents.
DKIM works in a similar way. It proves:
- The email really came from the domain that sent it.
- The message has not been altered while travelling across the internet.
If a cybercriminal intercepts an email and changes its content, the DKIM validation will fail.
Benefits of DKIM
- Confirms the email is genuine.
- Protects against message tampering.
- Improves trust with receiving email providers.
- Helps legitimate messages reach the inbox.
At Sprint Integration, we enable DKIM on Microsoft 365 domains as part of our email security best practice.
What Is DMARC?
Domain-based Message Authentication, Reporting and Conformance
DMARC is the intelligent decision-maker.
It works alongside SPF and DKIM and tells receiving email systems what to do when an email fails authentication checks.
A Simple Example
Imagine you have security guards at your office.
SPF is the reception team checking whether the visitor is on the approved list. DKIM checks whether their identity document has been tampered with.
DMARC tells reception what action to take if either of those checks fail:
- Allow them in.
- Send them to a waiting area for inspection.
- Refuse entry completely.
This gives domain owners far greater control over how fraudulent emails are handled.
DMARC Policies
DMARC generally operates in three stages:
p=none
Monitoring mode. Emails continue to be delivered, but reports are generated to show what is happening.
p=quarantine
Suspicious emails are usually delivered to the junk folder. This is often the recommended next step once monitoring has confirmed legitimate mail sources.
p=reject
Emails that fail authentication are rejected completely. This offers the highest level of protection but should only be enabled once SPF and DKIM are correctly configured.
Why Do You Need All Three?
Many businesses assume that Microsoft 365 or Google Workspace automatically protects them against email impersonation.
While these services provide excellent security, SPF, DKIM and DMARC still need to be configured correctly for your domain.
Think of them as:
| Technology | Purpose |
|---|---|
| SPF | Confirms who is allowed to send email |
| DKIM | Confirms the email hasn’t been altered |
| DMARC | Decides what happens when checks fail |
Together they provide a strong defence against:
- Phishing attacks
- Business email compromise
- Supplier payment fraud
- Fake invoice scams
- Domain impersonation
- Brand reputation damage
Without all three working together, your organisation may be more vulnerable to cybercriminals and your legitimate emails could be more likely to land in spam folders.
How Sprint Integration Can Help
Many businesses don’t know whether SPF, DKIM and DMARC are properly configured on their domains.
As part of our Microsoft 365 health checks and security reviews, Sprint Integration assesses email authentication settings and helps customers:
- Verify SPF records.
- Enable DKIM signing.
- Configure DMARC monitoring and reporting.
- Identify unauthorised email sources.
- Improve email deliverability.
- Reduce the risk of phishing and impersonation attacks.
Our internal health-check standards treat SPF, DKIM and DMARC alignment as an important part of a secure Microsoft 365 environment.
SPF, DKIM and DMARC may sound complicated, but their purpose is straightforward:
To prove that emails claiming to come from your business really are from your business.
Together they help protect your customers, staff and reputation from increasingly sophisticated cyber threats. They also improve the chances of your legitimate emails reaching their intended recipients.
In today’s cyber landscape, having these technologies correctly configured is no longer a luxury.
It is an essential part of protecting your organisation and maintaining trust in your communications.
