You can do it through DW, but it would require using some server-scripted code (ASP/PHP/ColdFusion). You could code it from scratch or edit a script provided by your hosting. Ask them what you should do.
You need a form-to-email processing script. Preferably one which conceals your e-mail address from harvesters and has built-in spam prevention.
Contact your web host and ask them if they have one you can use. Often hosts provide scripts on their servers which you can activate through your Admin Panel or by referencing the script in your form's action attribute.
If your host doesn't provide scripts, ask them which server-side languages you can use (php, asp, asp.net, perl, coldfusion, etc...).
Some Related Links:
Formm@ailer PHP from DB Masters
Forms to Go from Bebosoft (script generating software)
Wufoo.com (on-line form service)
Alt-Web Design & Publishing
Web | Graphics | Print | Media Specialists
I had the same issue. I solved it by odering AWeber. It proveds everything I neededto broardcast messages to my clients and save my responses into a database. Take a look at it may be more than you need, but is working for me. You can even create a coupon campaign. Go to AWeber.com to review.