Who This Is For / When to Use
Users sending email campaigns, automations, or one-to-one messages
Teams experiencing email delivery failures or high bounce rates
Accounts focused on maintaining a strong sender reputation and compliance
What Changed
Kyrios now validates email domains before sending and blocks messages to domains that are known to be invalid or restricted.
This validation happens automatically and requires no setup.
How Domain Blocking Works
Kyrios checks the recipient’s email domain before sending
If the domain is flagged as invalid or restricted, the email is not sent
The block happens instantly at the pre-send stage
This prevents failed delivery attempts and protects overall sending performance.
Pre-Send Email Validation
Kyrios performs validation before any email is sent.
This ensures:
Invalid email addresses are detected early
Restricted domains are blocked automatically
Emails are only sent to valid, safe recipients
User Notification for Blocked Emails
When an email is blocked due to a restricted or invalid domain, the following message appears:
“This email address is invalid as the domain is restricted for security reasons.”
This message confirms that the email was not sent and explains why.
Why This Matters
Improved Deliverability
Blocking invalid domains reduces bounce rates and increases inbox placement.
Protected Sender Reputation
Preventing sends to bad domains helps maintain domain and IP health.
Increased Platform Security
Restricting unsafe domains reduces risk and enforces compliance standards.
Clear Feedback for Users
Users receive immediate, actionable feedback when an email cannot be sent.
Common Issues and Fixes
Email not sending to a contact
Cause: The email domain is invalid or restricted.
Fix:
Verify the contact’s email address
Replace it with a valid, active domain
Retry sending the email
FAQ
Why was my email not sent?
The email was blocked because the recipient’s domain is invalid or restricted.
Can I override or bypass this restriction?
No. Domain blocking is enforced automatically to protect deliverability and security.
Does this apply to all email types?
Yes. This applies to all email sends, including campaigns, workflows, and one-to-one messages.
Do I need to enable this feature?
No. This functionality is built into Kyrios and works automatically.