If there isn't a "correct" answer posted, then you could almost certainly begin by first posting an answer of your own. Once yours is posted, you could then leave a comment to the poster of the other answer addressing the issue. Comments are after all intended to help the poster clarify a question or improve an answer, so leaving a note would be helpful.
As far as downvoting goes, that's really up to you. Some people like to silently downvote bad answers and move on, while others are happy to try to help the poster improve. If I downvote and leave a comment, I try to make it a point to revisit the post later to remove the downvote if the issue is resolved. Oftentimes, this happens in response to a user making the edit and then asking me to review. Hope this helps!
I left the following comment, to help clarify further:
Hi atmd, I think the downvote is because it sounds like you're suggesting the developer can cause mail to be sent automatically simply by using the "mailto:" link. This is not true, as a mailto link simply opens the default email client, requiring the user to manually fill out and manually send the email. You could fix your answer to clarify what you mean, which may avoid more downvotes or even reverse them. Good luck!