Email list quality score
Paste a sample of your list and get a grade in seconds. Every point is explained, the rubric is published below, and nothing you paste leaves your browser.
A few hundred rows from across the list is enough. The sample is scored in this tab and never uploaded.
The short version
- You get a score out of 100, a grade from A to F, and the rows behind every finding.
- 90 and up is an A: send, and verify before large campaigns. 70 to 89: fix the top finding first. Under 70: clean the list before it goes anywhere near your ESP.
- A few hundred rows taken from across the list gives a fair picture. Old and new addresses behave differently, so don't sample only the top.
- The score reads the text. An SMTP check tells you which mailboxes exist.
The rubric, in full
Each row is checked once. Repeats are counted as duplicates and not checked again. The rest go through the same syntax rules as our email syntax checker, the bundled list behind the disposable email checker, a one-or-two-letter typo check against large providers, and the role list ZapBounce flags.
Every finding is turned into a share of the sample. That share is multiplied by the weight in the table, and the points are taken off 100. So 2% role accounts costs 2 points, while 2% disposable addresses costs 6. Syntax and disposable weigh most because both are certain losses: the first hard bounces and the second reaches nobody.
You can redo the score by hand from the table the tool prints. There's no hidden factor and no benchmark against other lists.
| Finding | What it costs you | Points per 1% of the sample |
|---|---|---|
| Broken syntax | The string can't be an address, so it will hard bounce | 3 |
| Disposable domain | A throwaway inbox that is read once, if at all | 3 |
| Domain typo | One or two letters off a large provider, such as gmial.com | 2 |
| Duplicate | Sent twice, which doubles the chance of a complaint | 1 |
| Role account | Reaches a function, not the person who signed up | 1 |
| Score | Grade |
|---|---|
| 90 to 100 | A |
| 80 to 89 | B |
| 70 to 79 | C |
| 60 to 69 | D |
| 0 to 59 | F |
What to do with your grade
Start with the finding that took the most points. Typos are often fixable: if a signup form produced gmial.com, the person meant gmail.com, and a confirmation step at signup stops the next one. Disposable and broken rows can go straight away.
Then check the mailboxes. A list can score 100 here and still carry addresses that closed last year, since a real-looking address at a real company is only confirmed by the receiving server. ZapBounce asks that server over SMTP, closes before DATA so nothing is sent, and returns a result for every row. Duplicates and unknowns cost nothing.
Age matters too. If the list hasn't been verified in months, the list decay calculator estimates how much of it has moved since.
Questions people ask
How do I check the quality of my email list?
Paste a few hundred rows from across the list into the box above. You get a score out of 100 and a grade, built from five checks you can see: broken syntax, disposable domains, domain typos, duplicates and role accounts.
What is a good email list quality score?
A score of 90 or more is an A, and it means the problems the sample shows cost 10 points or fewer. Below 70, clean the list before you send, starting with the finding that cost the most points.
How is the email list quality score calculated?
Each finding costs points per percent of the sample it affects: 3 for broken syntax and disposable domains, 2 for domain typos, 1 for duplicates and role accounts. The score is 100 minus the total, and never below 0.
Does a good score mean my emails won't bounce?
The score reads what the text of the list shows. Whether each mailbox exists takes an SMTP check, which is what ZapBounce's verification does, with a valid, invalid, catch-all or unknown result for every address.
Grade the mailboxes as well as the text
Verify 100 addresses a month free with no card. Every row comes back valid, invalid, catch-all or unknown, with role and disposable flags.