If you want your participants to be able to email you through the mobile app, simply include a link to your email.
You can do this within the rich text editor by clicking on the "Link" icon. Under "Link Type" choose "Email". This will allow you to then prep-populate an email including the "To" email address, subject line, and email body if you wish. Or, you can leave the subject line and body empty. If you pre-populate it, then when a mobile user clicks on this link in the question text, it will open their email client and allow this email including subject line and body text to be sent. Alternatively, the mobile participants will be able to input their own subject line and body text.