Stop Paying for Unsendable Emails with Email Deliverability Add-On

Confirm email inboxes accept mail in real-time. Reject bad emails at ingestion, not after you’ve already paid for the lead. Layer it onto your Real Contact API call with a single parameter.

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API Documentation
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{
  • id: "Phone.3dbb6fef-a2df-4b08-cfe3-bc7128b6f5b4",
  • phone_number: "2069735100",
  • is_valid: true,
  • activity_score: 57,
  • country_calling_code: "1",
  • country_code: "US",
  • country_name: "United States",
  • line_type: "NonFixedVOIP",
  • carrier: "Level 3 Communications, LLC",
  • is_prepaid: false,
  • : {1 item}
}

Email Deliverability Use Cases

Block Fake Signups at the Form

Catch disposable and non-existent emails at account creation before they break 2FA and billing flows. Add one parameter to your existing Real Contact call for a clear pass/fail signal.

Protect Sender Reputation

Clean your list before every nurture, re-engagement, or broadcast campaign. Removing undeliverable addresses keeps bounce rates low and ensures messages actually reach an inbox.

Screen Inbound Leads Before You Reach Out

Verify emails at ingestion before they hit your CRM, scoring model, or sending infrastructure. Undeliverable emails drop to an F grade automatically, making it easy and fast to filter out bad leads.

See how many undeliverable emails are in your current list.

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Deliverability Intelligence, Built for Scale

Real-Time Inbox Verification

Every query pings the destination mail server in real time, validating whether the inbox actually exists and accepts mail. Returns deliverability status within the same API response with email validity and email contact grades.

Unified A–F Contact Grading

Deliverability results feed directly into Trestle’s A-F Contact Grades alongside Phone Activity Scores, address validity, and IP intelligence signals. One grade = clear decision logic based on your use case.

Built to Fit Your Workflow

Run it in real-time during lead ingestion, in the background after processing, or in bulk on a scheduled list cleanup. One add-on powers all three workflows, with the same grade returned every time.

Catches What Syntax Validation Misses

Detects accepting-but-dead inboxes, spam traps, abandoned mailboxes, and role-based addresses that pass basic validation but never convert. These are the emails that survive syntax or domain checks but still bounce in production.

Add-on Available In Real Contact API

Access Email Deliverability via API integration or Batch Upload — whichever fits your needs best.

  • API Integration

Seamlessly integrate with one parameter change to reject bad emails at ingestion and protect your sender reputation.

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  • Batch Upload

Include Email Deliverability when you upload CSV files for bulk verification. Select the add-on via checkbox and get results within minutes.

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Why Customers Choose Trestle

One API, Comprehensive Identity Signals

Email deliverability is one of many insights returned by a single Real Contact API call, alongside phone validity, Phone Activity Scores, address match, IP intelligence, name verification, and A-F contact grades. You don’t need to add another vendor, another integration, or another billing relationship.

Built for Real-Time and Batch at Enterprise Scale

3-second deliverability SLA on real-time queries. 99.99% uptime. Over 500 million queries served per month. The infrastructure that already runs your phone verification runs your deliverability.

Fast and Easy Integration

Add Email Deliverability to Real Contact API with a single parameter change and go live in minutes. Our clear, world-class API documentation and SDKs mean your team ships in minutes versus weeks.

Email Deliverability Add-on Pricing

Self-Service

+$0.005

/query

  • Pay for only what you use
  • Add to Real Contact API
  • Available via Batch Upload
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Enterprise

Custom Pricing

  • High-volume discounts
  • Enterprise support
  • Custom queries per second (QPS)
  • Dedicated integration assistance
  • Robust admin controls
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Frequently Asked Questions

How is this different from the email validation already in Real Contact API?

Real Contact API’s built-in email validation confirms syntax and that the domain exists and accepts mail. The Email Deliverability Add-on pings the specific inbox in real-time to confirm the mailbox itself exists and accepts mail. The two together catch syntactically valid emails that point to dead or non-existent inboxes, the category most responsible for bounces.

What’s the latency? Can I use this during signup?

Deliverability queries have a 3-second maximum response time. For most signup flows, that’s acceptable inline. If your signup form can’t tolerate 3 seconds, run the check asynchronously after signup and soft-reject or downgrade the user’s state on a failure. Both patterns are supported by the same add-on.

Do flagged emails automatically downgrade the Contact Grade?

Yes. When the Email Deliverability Add-on is enabled and the inbox returns undeliverable, the email portion of the contact grade is set to F, which pulls the overall grade down accordingly. You can gate on a signal grade signal instead of parsing the deliverability flag separately. 

Why isn't this included by default?

Real Contact API serves multiple use cases; some that need deep inbox verification (lead ingestion, signup protection) and some that don’t (caller verification, general contact lookup). The add-on pattern lets customers pay for the verification depth they actually need, rather than paying more on every call.

Start Catching Undeliverable Emails Today

Try the Email Deliverability Add-on for free, no credit card required.

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