The ‘This mail has been blocked because the sender is unauthenticated. 550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.’ is an email error generated by Google when sending email to Gmail based email addresses.
Here is an example of what the error looks like:
If you receive this error message from Google after sending to a Gmail email address, you need to enable SPF, DKIM and DMARC on the DNS zone for your domain name to clear the error. Please see below for steps.
SPF
SPF (Sender Policy Framework): An email authentication system that uses DNS to check if a mail server is authorized to send emails from your domain name.
- If your domain name is using Skystra Nameservers: Domain names connected to your hosting control panel and pointed to our network via Skystra nameservers will automatically have SPF enabled. You do not need to do anything.
- If your domain name is using External Nameservers: If you are using an external DNS and/or CDN provider (Cloudflare, etc.) – or an external email service, you will have to set up and manage your SPF record from your account at that provider. Please go here: Manage SPF record
DKIM
DKIM (DomainKeys Identified Mail): A system to authenticate your email, ensuring it genuinely came from your domain and that email truly originates from you.
- If your domain name is using Skystra Nameservers: Domain names connected to your hosting control panel and pointed to our network via Skystra nameservers will automatically have DKIM enabled. You do not need to do anything.
- If your domain name is using External Nameservers: If you are using an external DNS and/or CDN provider (Cloudflare, etc.) – or an external email service, you will have to set up and manage your DKIM record from your account at that provider. Please go here: Manage DKIM record
DMARC
DMARC (Domain-based Message Authentication, Reporting, and Conformance): A system that helps protect your domain name from being used for phishing or spam.
- If your domain name is using Skystra Nameservers: You can create a DMARC record on domain names connected to your hosting control panel. If your domain name is pointed to our network via Skystra nameservers, DMARC will activate after you create the record on your hosting control panel. Please go here: Enable DMARC on domain name
- If your domain name is using External Nameservers: If you are using an external DNS and/or CDN provider (Cloudflare, etc.) – or an external email service, you will have to create your DMARC record on your Skystra hosting panel and then set it up and manage from your account at the external DNS or CDN provider. Please go here: Enable DMARC on domain name