Validates credentials and password if exists in current session or generates ones for session time on empty password which is treated as one-time password request and sends it to an email. Matches only valid email from allowed domains using global allowemailaddresses and denyemailaddresses settings if set.

Additional security can be set:

Revoke threshold: login failures limit causing revoke of the generated password.

Minimum request period: a time in seconds after which another password can be generated.

Signup and user creation on first login takes place only in case of using email as username (not to be confused with the authloginviaemail global setting) if not prevented (global setting authpreventaccountcreation) and parts of email address may be mapped to profile fields using PCRE expressions.

Auth instruction setting (global auth_instructions) is recommended depending on the adopted user account policy and plugin settings.

See also: fieldsmapping_help setting form for mapping usage example.