This article explains how to combine a subscription page with a form or survey while eliminating the need to put an email address field on both pieces of web content. This also works between forms and surveys.
NOTE: Checkbox Form Fields on a Click Form can be mapped to Subscription Lists to record subscription preferences. However, Forms do not fulfill the requirement of including an opt-out method in emails; this still requires the presence of a global unsubscribe link or a direct link to a subscription management page.
You may often want to obtain subscription preference information from somebody at the same time as you obtain other information (such as contact information) using a form, but subscription pages only pre-populate with a person's preexisting preferences when sent via email. There is actually a simple way to directly link a form or survey and a subscription page so you can obtain all of this information at once while still pre-populating the subscription preferences.
Both forms and subscription pages are found in Web Content, which can be found at Web and Events > Web Content.
Begin by opening the Designer Windows for both your Form and your Subscription Management Page.
In the Subscription Management Page designer, click the the Embed button (this will open a new window), then copy the Subscription Management Page's Embed Link from the Embed as Link tab.
In the Form designer, click the Confirmation Text button (this will also open a new window).
Paste the Subscription Management Page's Embed link into the Post Redirect field at the bottom of the Form's Confirmation Text window. Add ?$EMAIL to the end of the subscription page link, then save and close the confirmation text window.
Now when the Form or Survey is submitted, it will immediately redirect to the Subscription Management Page. If the person completing the form filled out an email field or the form is being completed by a contact with a preexisting record in your CRM, and if the person has submitted subscription preferences before, then the preferences will be pre-populated on the subscription page. You can make the transition between the Form or Survey and Subscription Management Page more seamless by changing the text on the Form or Survey submit button to "Next" or "Page 2" or something similar, thus concealing the fact that the Form or Survey and Subscription Management Page are actually different records.