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Delivery issues

Common Issues with Email Delivery

Email delivery issues can occur for a number of reasons, often related to authentication mechanisms like SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting & Conformance). This guide will help you troubleshoot these common issues to ensure reliable email delivery from your Tibus-hosted domain.

SPF Failures

SPF records are DNS records used to indicate which mail servers are authorized to send email on behalf of your domain. When an email is sent, the recipient’s server checks if the email is coming from an authorized server. If your SPF record is not properly set up, your emails may be marked as spam or even rejected.

How to Fix SPF Issues:

  • Make sure your SPF record is correctly configured in your domain's DNS settings.
  • The SPF record should include all IP addresses and services authorized to send email on behalf of your domain.
  • A typical SPF record looks like this:
v=spf1 ip4:192.0.2.0/24 include:mail.tibus.net -all
  • The -all mechanism indicates that only the listed IPs are allowed to send email for your domain, which helps to prevent spoofing. Ensure you update the SPF record to include all third-party services that send emails for your domain.

DMARC Failures

DMARC is a protocol that builds on SPF and DKIM (DomainKeys Identified Mail) to give domain owners more control over how email from their domain is handled by recipient servers. It helps ensure that emails are not only coming from authorized servers but also properly authenticated.

How to Fix DMARC Issues:

  • Ensure you have a valid DMARC policy in place.
  • A DMARC record should be published in the DNS settings for your domain, and it usually looks like this:
v=DMARC1; p=none; rua=mailto:[email protected]; ruf=mailto:[email protected]; pct=100
  • The p field represents the action taken when authentication fails. Options include none (no action), quarantine (mark email as suspicious), or reject (block email).
  • Regularly review the reports (rua and ruf email addresses) to understand what delivery issues are occurring.

DKIM Issues

DKIM (DomainKeys Identified Mail) helps ensure the content of your emails hasn't been altered in transit by adding a digital signature. If DKIM isn’t set up correctly, your emails could fail authentication.

How to Fix DKIM Issues:

  • Make sure DKIM is set up on your email server. This typically requires adding a public key to your domain’s DNS records.
  • The email server signs outgoing emails with a private key, and recipients can verify this with the public key.

Tips for Reliable Email Delivery

  • Check Your DNS Settings Regularly: Ensure that SPF, DKIM, and DMARC records are up to date, especially if you change email providers or add third-party services.
  • Monitor Blacklists: Regularly check if your IP address is on any email blacklists, as this can affect delivery. Use tools like MXToolbox to scan for blacklisting issues.
  • Use Secure Ports: Use secure ports (587 for SMTP) and enable encryption (STARTTLS/SSL) to increase the likelihood of successful delivery.

If you need further assistance, please contact Tibus support for more detailed guidance on resolving email delivery issues.