The parsed addresses are a list of addresses that are syntactically valid (and optionally pass DNS and ESP specific grammar checks).
The unparsable list is a list of character sequences that could not be parsed (or optionally failed DNS or ESP specific grammar checks).
An email address identifies an email box to which email messages are delivered.
A wide variety of formats were used in early email systems, but only a single format is used today, following the standards developed for Internet mail systems since the 1980s.
Different email validation rates are given based on the API endpoint.
Both the public and private API endpoints are limited to a burst per minute rate.
Validating email address using regular expressions is tricky and is often not recommended. A valid email address as defined by RFC 2822 can be quite complex.