pub fn validate_email(field: &'static str, value: &str) -> Result<(), CoolError>Expand description
Pragmatic email check: requires exactly one @, non-empty local
and domain parts, at least one . in the domain, and no
whitespace. Not a full RFC 5322 grammar — that grammar admits
forms (quoted local parts, IP literals) banks rarely accept
anyway. Reject early; let real KYC flows do deeper validation.