IN THE FIELD GUIDE
tcp123
tcp123.com
TCP123 provides a free, instant domain email security audit focusing on SPF, DKIM, and DMARC alignment to prevent emails from Microsoft 365 and Google Workspace from being marked as spam. It performs passive public audits without infrastructure changes or data logging by interrogating global DNS and spam registries.
THE PRODUCT, BEYOND THE PITCH
Editorially reviewed · Sources checked Sep 17, 2026
A good fit for
- UK businesses seeking to secure their outbound email and prevent email delivery issues with Microsoft 365 and Google Workspace.
Know the limitations
- The scan only reads public DNS records and does not access passwords or mailboxes, so it cannot fix issues automatically.
- The service provides an audit and recommendations but requires users to implement fixes themselves.
What you can do
- Prevent business emails from being marked as spam by ensuring proper email authentication records are in place.
- Protect brand reputation by preventing attackers from impersonating the business via email.
Features
- Free security report in 30 seconds without signup, reading only public DNS records with no passwords or mailbox access.
- Checks SPF, DKIM, and DMARC records to identify email authentication gaps causing emails to land in spam folders.
- Scores each domain out of 100 based on SPF, DKIM, and DMARC security status, assigning letter grades from A+ to F.
Integrations
Not confirmed yet.
Platforms & data export
Not confirmed yet.
THE COST FOR YOUR TEAM
Go beyond the starting price.
Published plan prices for your team size and usage. Results update as you type. Taxes, currency conversion and unlisted add-ons are excluded, and anything the source did not state is called out rather than guessed.
Known monthly subtotal
$0.00/month
1 of 1 tools could not be priced with these inputs, so this is not the full cost.
| Tool / plan | Monthly | Per year | What this assumes |
|---|---|---|---|
| No pricing recorded yet. Check the official site, or ask the owner to add it. | |||
A practical workflow
- The scan interrogates global DNS and spam registries to assess SPF, DKIM, and DMARC alignment and generate an email security score.
- The results show which email authentication protocols are secured, warning, or missing, along with a score and letter grade to guide remediation.
Based on the sources below. Editorial review does not imply hands-on product testing.
Alternatives to explore
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Plan a switch from tcp123 →What changed
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