The service validates email addresses for compliance with standards detailed in internet requests for comment (RFCs). It verifies that the character count is within limits and that formatting reflects acknowledged best practices. Some internet service providers and email services generate noncompliant addresses, which may cause systems using strict validation to reject them as undeliverable. The service reduces this likelihood by catching and highlighting potential formatting problems. It makes no effort to confirm that email can actually reach a particular address, only that address formatting complies with applicable guidelines.
API methods allow submission of a character string and return a status of 1 or 0 indicating valid or invalid, along with diagnostic text describing any validity problem.