Settings / DNS

Use system default - if this option is checked, Atomic Mail Verifier will try load system default DNS settings.

Use specified DNS values - if this option is checked, you are asked to enter custom DNS server addresses in Primary and Secondary fields.

Threads count - Specifies the number of threads that work simultaneously when checking domain names. Setting this value to very small number of threads (less than 5) or large number (more than several hundreds depending on your computer performance) may significantly slow down the entire process.

Retries count - specifies the number of retried connections to each DNS server. The recommended setting is 2-3 retries (if the DNS server does not respond after 2-3 retries move on to the next DNS server on the list)

Common Settings
SMTP Settings
Email Filters Settings