@Mikal K Create a landing page to gather values, then use a JavaScript redirect to the malto:. However, be warned that mailto: links launched via regular web pages are not as functional as most people think they are. I've posted a couple of screencaps about this.
If a user uses a webmail app as their primary email and has not taken the (sometimes extraordinary) steps to set up the webmail as their mailto: handler, then clicking on a mailto: link
outside of the webmail app itself will try to start their local mail app, be it Outlook Express or Apple Mail or whatever, which is most likely not configured. It's a user experience disaster IMO.
This problem does not usually occur if the mailto: link is clicked directly within the webmail app, because the app is smart enough to hook mailto: links and steer you to a New Message pane within the app itself.
For the above reasons it is recommended that you use the `mktNoTrack` class on mailto: links in your emails, so they don't try to bounce off the Marketo click tracking server.
I mention all this because your scenario is basically reintroducing the problems that occur if you don't use `mktNoTrack.` You want to send people to a web page and then back to their mail client, and that is known to break. It would be better, far better, to send them to a form where they can send you an email.