Overview
Email address validation systematically checks each address on your mailing list before you send emails. It uses a series of technical methods and specialized algorithms to confirm whether an email address is authentic, correctly formatted, and able to receive mail. This process helps marketers identify and remove invalid, risky, or low-quality addresses, ensuring your emails are delivered safely and efficiently to their intended recipients.
Capabilities
The email address validation service combines the following techniques and detection mechanisms to provide highly accurate results:
1. Invalid addresses (INVALID)
Meaning: The address is invalid or does not exist. We recommend blocking these addresses to prevent hard bounces.
Sub-status | Description | Benefit |
| RFC-compliant address check | Blocks obviously malformed emails (e.g., |
| Misspelling check | Catches user input errors to avoid sending to non-existent addresses and reduce your bounce rate. |
| Domain MX record existence check | Identifies whether the recipient's domain can receive email, preventing sends to domains without a configured mail server. |
| IP unreachability check | Troubleshoots infrastructure issues by quickly identifying addresses that are physically unreachable due to incorrect domain configuration or offline servers. |
| Mail acceptance check | Protects sender reputation by avoiding sending to servers that are configured to reject all mail. |
| Mailbox full check | Identifies certain soft bounce scenarios, preventing unnecessary retries. |
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| Disabled account check | Identifies deactivated accounts to avoid wasting resources. |
2. Catch-all addresses (CATCHALL)
Meaning: This domain is configured to accept email sent to any address, making it impossible to determine if a specific mailbox truly exists.
Description: Identifies if an email address belongs to a catch-all domain. The servers for these domains accept all mail sent to them, even if the user part (the text before the @ symbol) does not exist.
Common providers: qq.com, mail.ru, Microsoft O365, and others (depending on whether the domain enables catch-all).
Benefit: Avoiding these addresses improves delivery accuracy and conserves resources.
3. Indeterminate addresses (UNKNOWN)
Meaning: The service cannot provide a definitive validation result at this time due to network issues or problems with the recipient's mail server.
Sub-status | Description | Benefit |
| Timeout control | Prevents long-running connections from slowing down the workflow and affecting overall validation throughput. |
| Intelligent graylist retry | Ensures business continuity by distinguishing between temporary network fluctuations and permanent failures. The retry mechanism can recover from false negatives caused by rate limiting. |
| Connection failure check | Identifies network connectivity issues or an offline recipient server. |
| System error | Indicates that you should retry the validation or skip the address. |
4. Atypical or high-risk addresses (DONOTMAIL)
Meaning: Although these addresses can receive mail, sending marketing campaigns to them is not recommended. Remove them from your marketing lists.
Sub-status | Description | Benefit |
| Role account identification | Improves marketing precision. A role account is often shared or automatically filtered, leading to extremely low engagement. Removing these addresses helps you target real individuals and optimize ROI. |
| Disposable address check | Prevents malicious registrations and fake accounts by ensuring users are genuine and interested in long-term engagement. |
| MX forwarding check | Mitigates delivery risks. Forwarding chains often have high latency, complex bounce rules, or privacy-masking issues. Identifying these addresses helps you avoid misinterpreting delivery failures. |
5. Advanced detection capabilities (FULL mode only)
The following capabilities involve real-time interaction with the recipient's mail server, which introduces higher latency. They are enabled only in FULL mode:
SMTP probe: Simulates an SMTP protocol interaction to directly verify if the user part of an email address exists and can receive mail. This effectively identifies a hard bounce (e.g., user does not exist) and some soft bounces (e.g., mailbox is full or disabled).
Note: You can enable or disable this feature using the
ProbeTypeAPI parameter.
Supported email service providers (ESPs) include: Gmail, Outlook, Yahoo, Tencent, Netease, iCloud, Proton, Zoho, GMX, Web.de, Mail.com, Mail.ru, Kakao, Naver, Nate, GoDaddy, Namecheap, Yandex, Mimecast, Proofpoint, Barracuda, Cisco, TrendMicro, and Symantec. Support for additional ESPs is planned.
Even for supported ESPs, the service may return an
UNKNOWNstatus due to insufficient system resources or an error from the recipient's server.
6. Additional returned fields
In addition to the validation status, the API returns the following fields to help you with list hygiene and data cleansing:
Returned field | Description | Benefit |
| Email provider profiling | Allows you to adjust your sending frequency to align with the anti-spam policies of different providers. |
| Free email check | Helps distinguish between business and personal email addresses (useful in B2B validation scenarios) to analyze user demographics. |
| Standardized address parsing | Data deduplication and cleansing. Identifies different aliases for the same user, enabling more accurate user deduplication. |
| Standardized address parsing | Facilitates data statistics and matching. |
Usage
You can use the email address validation service through the online console, the API, or by integrating it via a configuration set.
These methods allow you to seamlessly integrate the service into your existing systems, applications, or workflows.
Online console validation: Use the web-based interface for single or bulk validation. This method is ideal for quick, ad-hoc checks or users who prefer a non-programmatic approach.
Documentation: Address validation console instructions
API integration: Call the API to retrieve real-time validation results for single or bulk email addresses. This method is perfect for embedding validation into your automated workflows.
Documentation: How to use the email address validation API?
Use a configuration set: Automatically enable validation rules when creating a sending task. This allows you to filter out invalid addresses at send time without additional development, effectively reducing your bounce rate.
Documentation: Sending configuration (configuration set)
Billing
Each DM instance includes a free trial of 10 address validations.
These suppressed sends still count toward your daily sending quota and incur standard sending fees in addition to validation fees.
Detection mode | Description | Billing rules |
FULL | Enables all detection capabilities, including the interactive SMTP probe. | • Billed per valid result: Each successfully validated address counts as one validation. |
BASIC_ONLY | Enables all detection capabilities except the SMTP probe (e.g., syntax, DNS, and MX record checks). | • Billed per request: Each request is billed, regardless of the result. |
To purchase, go to the Direct Mail console, select Overview > Email Address Validation, and then click Purchase Service.
The pricing for the email address validation feature is as follows:
Tier (validations) | Price (USD) |
10,000 | 70 |
30,000 | 180 |
50,000 | 275 |
100,000 | 500 |
200,000 | 800 |
500,000 | 1,750 |
1,000,000 | 3,000 |
For descriptions of the email address validation statuses, see Validate Email Address.