Validation Types
TrueMail offers two ways to validate email addresses. Each method has different accuracy levels and credit costs, so you can choose what works best for your needs.
MX Validation (Basic)
Cost: 1 credit per email
MX validation checks if the email domain has valid mail servers configured. It’s fast, affordable, and catches the most common issues.
What it checks:
- Email syntax is correct (proper format like
[email protected]) - Domain exists and is registered
- Domain has MX (mail exchange) records pointing to mail servers
- Domain isn’t on known disposable email lists
Best for:
- Large lists where speed matters
- Initial cleaning before a campaign
- Signup forms where you want quick feedback
- Budget-conscious validation
Limitations:
MX validation confirms the domain can receive email, but can’t verify if the specific mailbox exists. For example, it would approve [email protected] since Gmail’s servers exist, even if that exact address doesn’t.
SMTP Validation (Advanced)
| Cost: 10 credits per email | Premium plan required |
SMTP validation goes further by connecting to the mail server and checking if the specific email address exists. This catches invalid addresses that pass MX validation.
What it checks:
Everything in MX validation, plus:
- Connects to the recipient’s mail server
- Checks if the specific mailbox exists
- Detects catch-all domains (servers that accept any address)
- Identifies full or disabled mailboxes
Best for:
- High-value email campaigns
- Lists you’ve collected over time that may have stale addresses
- Reducing bounce rates to protect sender reputation
- When deliverability is critical
Why it costs more:
SMTP validation requires real connections to mail servers, which takes more time and resources. The higher accuracy is worth it when bounce prevention matters most.
Quick Comparison
| Feature | MX Validation | SMTP Validation |
|---|---|---|
| Credits | 1 | 10 |
| Speed | Very fast | Moderate |
| Checks domain | ✓ | ✓ |
| Checks mailbox | ✗ | ✓ |
| Detects catch-all | ✗ | ✓ |
| Plan required | All plans | Premium |
Which should you use?
Choose MX validation when:
- You have a large list and want to remove obvious bad addresses
- Budget is a concern
- You’re doing initial list hygiene
Choose SMTP validation when:
- You’re sending important campaigns
- Your sender reputation is critical
- You want the highest possible accuracy
- The list hasn’t been validated recently
Setting validation type
In the dashboard
When uploading a list, select your preferred validation type from the dropdown.
Via API
Include the validation_type parameter in your request:
curl -X POST https://api.truemail.app/v1/verify \
-H "Authorization: Bearer YOUR_API_KEY" \
-d '{"email": "[email protected]", "validation_type": "smtp"}'
Valid values: mx or smtp
If not specified, MX validation is used by default.