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Domain spoofing poses a serious threat to email integrity and security. This issue arises when attackers impersonate a domain they don’t own, often for malicious purposes like phishing or distributing malware. To counteract domain spoofing, three security measures—DKIM, SPF, and DMARC—operate together on the open internet to authenticate emails and prevent fraudulent activities. These protective layers are effective on the open internet. However, in a closed, multi-tenant email delivery service like JetEmail, where multiple domains use a shared IP space for sending emails, relying solely on SPF to secure your domain against spoofing is inadequate. Domain Security enables you to specify which JetEmail SMTP users are authorized to send emails from your domain by setting your preferences in a DNS TXT record.

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DNS Record

Name: _jm.domain.com TTL: 14400 Value: 
v=jm1 auth=jetemail

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Finding your UUID

SMTP usernames are no longer exposed in email headers. Instead, each SMTP user is identified by a UUID in the X-JetEmail-User header. You can find your UUID by looking through the internet / email headers for X-JetEmail-User. It should look like this: 
X-JetEmail-User: 550e8400-e29b-41d4-a716-446655440000
You can also find your UUID in the JetEmail dashboard under your SMTP user settings.

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Authenticating with UUID or username

Domain Security supports both UUIDs and SMTP usernames in the auth field. We recommend using UUIDs as they match the headers and do not expose your username. 
v=jm1 auth=550e8400-e29b-41d4-a716-446655440000
You can also still use your SMTP username: 
v=jm1 auth=jetemail

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Authenticating multiple accounts

You can add multiple auth entries for multiple accounts, for example: 
v=jm1 auth=550e8400-e29b-41d4-a716-446655440000 auth=660f9500-f39c-52e5-b827-557766550111

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Blocked Messages

If your message does not authenticate, the mail will bounce with a message similar to this:

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Further Assistance

You can contact our support team any time should you have any questions or issues related to Domain Security.