The **address‑rfc2821** package is a lightweight Node.js library that parses and formats SMTP envelope email addresses according to RFC 821/2821/5321 (including UTF‑8 and punycode support). It’s aimed at mail server developers—especially those building or extending Haraka—to reliably handle the `<user@host>` syntax used in `MAIL FROM:` and `RCPT TO:` commands.