Welcome to BulkVerifier, an efficient multi-threaded application for checking e-mail addresses and domain availability. Quickly and easily verifies email addresses, huge domains and clean up your mailing / domain list. A powerful advanced bulk domain and email validation tool.

BulkVerifier v2.2 (New version!) offers you two processing modes fast and deep.

In its fast mode BulkVerifier works extremely fast being able to process mailing lists containing dozens of millions of e-mail addresses at a speed of several thousands addresses per second. This mode does not ensure the highest accuracy of checking/cleaning but is optimal by expended time and traffic and provides quite sufficient results. We recommend the fast processing mode of BulkVerifier as a high-speed tool for sifting obvious rubbish out of large mailing lists containing millions of e-mail addresses.

In its deep mode (default), BulkVerifier works significantly slower but provides much more precise results. Optimal data amount for this mode is 70...100 thousand e-mail addresses. We recommend the deep processing mode of BulkVerifier as a slow but high-quality tool for checking of not very large mailing lists.

Fast mode of BulkVerifier

In this mode BulkVerifier is able to process mailing lists containing dozens of millions of e-mail addresses at a speed of several thousands addresses per second. To switch to this mode please UNcheck the option Advanced e-mail check using SMTP in the Bulk Verifier Options dialog (see also the section Bulk Verifier interface and options).

Working in the fast mode, BulkVerifier determines about 25-30% of unavailable e-mail addresses in a mailing list. These figures may seem weak since theoretically up to 70% of unavailable e-mails can be determined in a list using software methods, but in fact these 30% can amount to 10% of the whole mailing list, which is quite significant.

More precise check which allows to define another 40% of unavailable e-mails is still available in the List check deep mode. But you should realize that the deep check may sometimes take 10 times more time and 5 times more network traffic, which often makes its use not quite reasonable for large e-mail lists.

In the fast mode, Bulk Verifier uses the stage of DNS requests to check e-mail addresses availability. During an e-mail address availability check the following actions are executed:

  • 1. BulkVerifier parses the address syntactically and singles out its mail domain.
  • 2. The top-level domain is singled out from the mail domain (e. g. .com for the mail domain mail.com).
  • 3. BulkVerifier compares the top-level domain with the basic top-level domains list stored in the application’s main folder (the file BulkVerifier.tld). If the initial e-mail address is syntactically incorrect or its top-level domain was not found in the file BulkVerifier.tld, the address is regarded as invalid. The further processing is not performed for this address.
  • 4. BulkVerifier requests the DNS server for the mail server address of the mail domain. If the DNS server returns one or more addresses of mail servers which accept mail for the domain, the initial e-mail address is considered available and valid. If the address was not found by the DNS server at all or there are no mail servers which accept mail for the domain, the initial e-mail address is considered invalid. If the DNS server could not return a response because DNS servers serving the mail domain were unavailable, the initial address is considered invalid.