> ## Documentation Index
> Fetch the complete documentation index at: https://developer.moltsets.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Understanding Email Risk Scores

> Why some emails are flagged "invalid" by other tools, and how MoltSets' Email Risk Score gives you a more accurate way to decide who to send to.

## Why you might see more "invalid" results from other tools

In spring 2026, Microsoft began blocking SMTP-based email validation checks. Because of this, third-party validation vendors (NeverBounce, ZeroBounce, and others) have started marking fully configured, deliverable inboxes as "invalid" — even though these addresses can receive mail and should be sent to.

## How MoltSets addresses this

To keep things transparent, MoltSets assigns every email an **Email Risk Score**. This score reflects what we actually know about deliverability, rather than relying solely on SMTP checks that are increasingly unreliable.

| Score | What it means                                  | Recommendation |
| :---- | :--------------------------------------------- | :------------- |
| **A** | Valid — known reply, open, or click            | Send           |
| **B** | Known send with no bounce                      | Probably send  |
| **C** | Catch-all                                      | Your call      |
| **D** | Hard invalid — bounce, complaint, or spam trap | Don't send     |
| **F** | No data available                              | Your call      |

## How it works

The Email Risk Score is appended to each record in the API payload. You retain full control over which emails to send to based on this score and your own risk tolerance.

## Best Practices for Using Email Risk Scores

Treat the grade as a filter, not a guarantee. A "Send" recommendation lowers risk, it doesn't eliminate it. Always pair risk scores with your own sending domain reputation and list hygiene practices.

### By Grade

| Grade | Best Practice                                                                                                                                                     |
| :---- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **A** | Safe to send to immediately. Strongest engagement signal available.                                                                                               |
| **B** | Solid to include in regular sends. For reputation-sensitive campaigns (e.g. cold outreach on a new domain), consider a smaller batch size before scaling up.      |
| **C** | Deliverability can't be confirmed. Segment separately from A/B, warm with lower volume, watch engagement closely, and suppress non-responders after 1-2 attempts. |
| **D** | Never send. Fastest way to trip spam traps and damage sender reputation for the whole list.                                                                       |
| **F** | Treat as unknown risk, not safe. Re-verify before sending, or route into the same cautious treatment as C.                                                        |

### General Sending Hygiene

* Suppress D scores automatically at the list level rather than relying on manual review
* Monitor bounce rate by grade over time to validate the scoring is holding up for your specific use case
* If sending cold outreach, warm up new domains regardless of score tier
* Re-score contacts periodically; email validity decays over time (job changes, inbox closures)