Replace the RFC 5322 mega-regexp with net/mail.ParseAddress, which is the
standard library's address parser and far easier to audit. A bare address
is required: inputs with a display name, angle brackets, a comment, or
trailing content are rejected, as is an address list.
Behaviour change: ParseAddress does not require the domain to contain a
dot, so "alice@localhost" now validates. Layer Match or a DNS lookup on
top if a stricter domain is needed.
Also rewrites FuzzEmail, which previously asserted that *every* input is
invalid, into checks that Email never returns an unexpected error type,
never panics, and gives a stable verdict.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
aneurinandClaude Sonnet 5