Function decodeMIMEHeader

internal/relay/server.go:773–782

decodeMIMEHeader decodes any RFC 2047 encoded-word runs in a header value (e.g. `=?utf-8?Q?caf=C3=A9?=` → `café`). Used for display fields like Subject so downstream consumers (DB, list summaries, dashboard) see the UTF-8 form instead of the wire-encoded form. If decoding fails the original value is

(v string)

// UTF-8 form instead of the wire-encoded form. If decoding fails the original
// value is returned — preserving the field is better than dropping it.
func decodeMIMEHeader(v string) string {
	if v == "" {
		return v
	}
	decoded, err := (&mime.WordDecoder{}).DecodeHeader(v)
	if err != nil {
		return v
	}
	return decoded
}

// extractAddressList parses an RFC 5322 address-list header (To/Cc) into bare
// email addresses, dropping display names. Returns nil if the header is empty