isValidEmail

Returns true if this String looks like a valid email address.

This is a pragmatic, permissive check rather than a full RFC 5322 implementation: it accepts the common local-part characters (letters, digits, and ._%+-, so plus-addressing works), single-character domain labels, modern long TLDs, and bare IPv4-literal domains. It does not accept quoted local parts, internationalized (Unicode) domains, or bracketed/IPv6 address literals.