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Domain Verification

The "Verify Domains" utility has two operating modes:

  • Verify domains of email addresses in these files (Verify Domains Of Emails In These Files).
  • Verify domain lists (Verify Domain Lists).

These modes differ in that when verifying email addresses, the first step is extracting domains from the email list. Then the domain list is verified (Verify Domain Lists). After that, the original email list is filtered: only email addresses from valid (verified) domains are retained.

Multi-Column Support

In "verify domains of email addresses" mode, enable this setting if the input list contains multiple columns.

Number of Threads

Domain verification is performed in parallel using multiple threads. You can set the number of threads (Number of threads). Recommended value: 100. Too many threads may cause performance degradation and instability.

Timeout

Timeout allows limiting the time (in seconds) for domain verification. Recommended value: 20.

DNS Query

You can choose which DNS query (Query DNS) is used for domain verification:

  • MX — DNS record used for routing email via the SMTP protocol.
  • A — DNS record that maps a domain name to an IP address.

Example MX Record Results

aim.com,mx-aol.mail.gm0.yahoodns.net
aol.co.jp,mail.aol.co.jp

Suppress MX from Other Domains

In the example, the MX record for aim.com points to another domain (yahoodns.net). The setting Suppress MX from domains other than verified allows excluding such records.

Keep / Exclude

Keep and Exclude allow filtering domains by country. For example, to keep only domains from the US, enable Keep and enter the country code: US.

Domain Verification Settings

Click the Additional Options button to open the domain verification settings dialog.

GEO Database

The GEO database (IP 2 Country Database) allows retrieving a country code for a given IP address. Format: CSV (Comma Separated Values). The first two columns define an IP range. The third column contains a two-letter country code. Example:

1.1.0.0,1.1.0.255,CN
1.1.1.0,1.1.1.255,AU
1.1.2.0,1.1.3.255,CN
1.1.4.0,1.1.7.255,CN

WHOIS Query

WHOIS queries (via whois.arin.net) can be used to determine the country. However, this method is not recommended because WHOIS data does not always contain reliable country information.

DNS Settings

It is recommended to specify DNS server IP addresses (Use custom DNS servers). For example, Google DNS:

8.8.8.8
8.8.4.4

Timeout is the time (in seconds) to wait for a DNS response. Recommended value: 15 seconds. Too high values may slow down verification, while too low values may cause failures due to insufficient response time.

Retries is the number of attempts to query the DNS server if previous attempts fail.

Connection Settings

Connect to Port is the port used for connection when "Try connect" is enabled. Usually this is set to 25 (SMTP). See Common TCP Ports.

IP Rotation allows specifying network interfaces from which connections are made. Example:

192.168.1.110
192.168.56.1

Output Emails File

In "verify domains of email addresses" mode, the Output emails file contains email addresses from domains that passed verification.

You can enable Save resolved ip/domains to output file to include IP addresses and MX records. Example:

user1@google.com,smtp.google.com

Good Domains

The Good Domains file contains domains that passed verification.

You can enable Save resolved ip/domains to output file to include IP and MX information. Example:

google.com,smtp.google.com

Bad Domains

The Bad Domains file contains domains that failed verification.

Remove Domains

You can filter (remove) domains that have the same MX records as specified ones (Remove domains having same MX records as these domains). Example:

internetdefensesystems.com

The domain internetdefensesystems.com has MX record mx152.viahttps.com. All domains with the same MX record will be removed.

Remove MX Records

You can filter domains that have specific MX records (Remove domains having these MX). Example:

mx152.viahttps.com

Remove MX Records with IP Addresses

You can filter domains whose MX records resolve to specific IP addresses (Remove domains having MX with these IP). Example:

75.51.0.152

Remove NS Records

You can filter domains that have specific NS records. Example:

ns2.wetrag.net