Implementing SPF, DKIM, and DMARC with Campaign Monitor
TABLE OF CONTENTS
A set of methods meant to confirm the validity of an email’s sender and guard receivers against phishing, spoofing, and other malevolent behavior called email authentication. Email authentication is dominated three-key protocols: DMARC (Domain-based Message Authentication, Reporting, and Conformance), DKIM (DomainKeys Identified Mail), and SPF (Sender Policy Framework).
SPF lets domain owners indicate which mail servers are allowed to send emails on behalf of their domain. DKIM digitally signs emails to confirm the contents haven’t been altered on route. Building on both SPF and DKIM, DMARC offers a structure for domain owners to indicate how their emails should be handled should authentication tests fall short.
Popular email tool Campaign Monitor understands the value of these authentication techniques and offers strong encouragement for their application. Using Campaign Monitor’s tools and adhering to best standards can help you greatly improve email deliverability and safeguard brand reputation.
Understanding why email authentication is required and how it operates to safeguard senders and recipients will help one to appreciate the implementation specifics later on.
Malicious actors utilize email spoofing – a method whereby they create the sender’s address – to provide the email seeming origin from a reputable source. Phishing attempts, in which thieves try to fool victims into disclosing sensitive information or clicking on dangerous links, sometimes use this approach.
From data breaches and financial losses to brand reputation damage, the results of effective spoofing and phishing campaigns can be dire. Conventional email security policies are insufficient as these hazards change.
Email authentication systems enable recipient mail servers to confirm that an email really comes from the domain it claims to be from. This checking procedure aids in:
1. Stop illegal email forwarding of your domain.
2. Less likely are your emails labeled as spam.
3. Save the standing of your brand.
4. Raise general email deliverability
Although every one of these systems can be employed on its own, they are most effective when combined: :
1. SPF confirms that the transmitting server is authorised to email for your domain.
2. DKIM guarantees that the email content hasn’t changed on route.
3. DMARC links DKIM and SPF so that domain owners may control how to handle email authentication attempts and get feedback on failures.
An email authentication system called Sender Policy Framework (SPF) lets domain owners indicate which mail servers are authorised to send emails on behalf of their domain. It’s meant to stop spammers from delivering messages using phoney “From” addresses from your domain.
SPF adds a DNS TXT record to your domain listing the IP addresses or hostnames of the servers authorised to send email on behalf of your domain. A receiving mail server examines this SPF record when receiving an email purportedly from your domain. The email passes SPF authentication if the IP address of the sender server shows on the SPF record.
Let’s walk through the process of implementing SPF with Campaign Monitor:
1. Accessing DNS records. Log into your domain registrar or DNS hosting provider’s control panel. Look for an option to manage DNS records or add TXT records.
2. Creating an SPF record. Add a new TXT record with the following format:
v=spf1 include:cmail1.com include:cmail2.com ~all
This record includes Campaign Monitor’s sending servers (cmail1.com and cmail2.com) and uses a soft fail (~all) for other servers.
3. Verifying the SPF record. After adding the record, wait for it to propagate (this can take up to 48 hours). You can verify your SPF record using online SPF checking tools.
Here’s an example of how your DNS records might look after adding the SPF record:
Type Host Value TXT @ v=spf1 include:cmail1.com include:cmail2.com ~all
Using public-key cryptography to sign email messages, DomainKeys Identified Mail (DKIM) is an email authentication tool that lets the recipient confirm the email was really sent and approved by the domain owner.
DKIM operates by adding a digital signature to email message headers. The sender generates this signature with a private key kept under control; it can be checked with a public key released from the DNS records of the domain. Should the signature be valid, it indicates that the email arrived from an authorised sender and was not changed in route.
Here’s how to implement DKIM with Campaign Monitor:
1. Generating DKIM keys. Campaign Monitor handles this step for you. They generate and manage the private keys used for signing your emails.
2. Adding DKIM record to DNS. Campaign Monitor will provide you with a DKIM record to add to your DNS. It will look something like this:
Name: cm._domainkey
Type: TXT
Value: k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrLHiExVd55zd/IQ/J/mRwSRMAocV/hMB3jXwaHH36d9NaVynQFYV8NaWi69c1veUtRzGt7yAioXqLj7Z4TeEUoOLgrKsn8YnckGs9i3B3tVFB+Ch/4mPhXWiNfNdynHWBcPcbJ8kjEQ2U8y78dHZj1YeRXXVvWob2OaKynO8/lQIDAQAB;
Add this record to your domain’s DNS settings.
3. Verifying DKIM setup. After adding the record and waiting for it to propagate, you can verify the setup using DKIM checker tools available online.
Here’s an example of how your DNS records might look after adding the DKIM record:
Type Host - Value
TXT cm._domainkey - k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCrLHiExVd55zd/IQ/J/mRwSRMAocV/hMB3jXwaHH36d9NaVynQFYV8NaWi69c1veUtRzGt7yAioXqLj7Z4TeEUoOLgrKsn8YnckGs9i3B3tVFB+Ch/4mPhXWiNfNdynHWBcPcbJ8kjEQ2U8y78dHZj1YeRXXVvWob2OaKynO8/lQIDAQAB;
Based on SPF and DKIM, DMARC – Domain-based Message Authentication, Reporting, and Conformance – is an email authentication system. It gives domain owners a means to receive reports about attempts at email authentication and lets them indicate how to treat emails that fail authentication.
DMARC uses email passing SPF and/or DKIM authentication to operate. It then chooses how to handle the email using the policy the domain owner selected. Reaching servers can be directed by this policy to deliver, quarantine, or refuse emails failing authentication.
Here’s how to implement DMARC with Campaign Monitor:
1. Creating a DMARC policy. Start with a minimal DMARC record:
v=DMARC1; p=none; rua=mailto:[email protected]
2. Adding DMARC record to DNS. Add this as a TXT record to your DNS settings:
Type: TXT Host: _dmarc Value: v=DMARC1; p=none; rua=mailto:[email protected]
Here’s an example of how your DNS records might look after adding the DMARC record:
Type Host Value TXT _dmarc v=DMARC1; p=none; rua=mailto:[email protected]
4. Using DMARC Generator tools. For those who find creating DMARC records challenging, tools like the DMARC Generator at can be incredibly helpful. This user-friendly tool simplifies the process of creating accurate DMARC records, making it easier to implement this crucial email authentication method.
While the basic setup of SPF, DKIM, and DMARC can significantly improve your email authentication, there are advanced configurations that can further enhance your email security and deliverability:
- SPF:
- Use the
ip4:andip6:mechanisms to specify exact IP addresses. - Utilize the
a:mechanism to include all IPs associated with a domain. - Implement SPF flattening to avoid exceeding the 10 DNS lookup limit.
- Use the
- DKIM:
- Implement key rotation to regularly update your DKIM keys.
- Use longer key lengths (2048 bits) for enhanced security.
- Consider using multiple DKIM selectors for different email streams.
- DMARC:
- Gradually increase your DMARC policy from
p=nonetop=quarantinetop=reject. - Implement subdomain policies using the
sp=tag. - Use the
pct=tag to apply policies to only a percentage of your emails during testing.
- Gradually increase your DMARC policy from
Remember, these advanced methods should be implemented carefully and with thorough testing to avoid disrupting your email flow.
Even with careful implementation, you may encounter issues with your email authentication setup. Here are some common problems and how to address them:
Common SPF syntax errors include:
- Missing or incorrect version string (
v=spf1) - Too many DNS lookups (exceeding the 10 lookup limit)
- Incorrect use of mechanisms or qualifiers
To resolve these, double-check your SPF record syntax and use online SPF validation tools to identify specific errors.
DKIM issues often arise from:
- Incorrect copying of the public key into DNS
- Mismatched selectors
- Expired or revoked keys
Verify that your DKIM record in DNS exactly matches what Campaign Monitor provided. If issues persist, you may need to generate and implement new DKIM keys.
DMARC problems can occur due to:
- Overly strict policies implemented too quickly
- Misconfiguration of SPF or DKIM
- Legitimate emails failing authentication
Start with a monitoring policy (p=none) and analyze your DMARC reports before implementing stricter policies. Ensure all legitimate email sources are covered by your SPF and DKIM configurations.
While implementing SPF, DKIM, and DMARC is crucial for email authentication, it’s equally important to maintain a good sender reputation. This is where email warm-up services like Warmy.io come into play.
Email warm-up is the process of gradually increasing your email sending volume to establish a positive sender reputation with ISPs. Warmy.io automates this process, helping you to:
- Improve your sender reputation
- Increase email deliverability
- Reduce the chances of your emails landing in spam folders
Warmy.io offers a range of free tools to help you optimize your email deliverability, including:
- Email Deliverability Test. This comprehensive test checks various factors that influence email deliverability. It provides insights into potential spam triggers, checks if your domain is on any blacklists, and offers recommendations for improvement.
Your whole email deliverability will be much improved by integrating appropriate email authentication (SPF, DKim, DMARC) with email warm-up services like Warmy.io to guarantee your messages reach their intended receivers.
Securing your email communications and enhancing deliverability depend on first using SPF, DKIM, and DMARC with Campaign Monitor. Following the advice in this book will help you to properly verify your emails, guard your domain from spoofing, and learn a great deal about your email environment.
Recall that email verification is an active process. Maintaining current records, routinely check your authentication reports, and keep informed about fresh email security advancements. By means of appropriate implementation and maintenance of these procedures, you may guarantee that your emails regularly find their inboxes, therefore preserving the faith and involvement of your recipients.
Finally, remember to maximize your email deliverability with other tools and services including Warmy.io. Strategic warm-up routines combined with strong authentication techniques can help you to maximize the impact of your email marketing campaigns.
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