This domain is associated with a disposable or temporary email service. Users can create throwaway email addresses that expire after a short period.
crankymonkey.info is a known disposable email provider. Any email address @crankymonkey.info is temporary — designed for one-time use and typically expires within hours or days.
Services like this are popular for avoiding spam, but they're also frequently used to abuse free trials, create fake accounts, or bypass email verification. Consider blocking signups from this domain.