When there is more than one form of the same type on the same page (for example contact form in the footer, when the contact form is displayed, using line view to render link) and one is submitted, second is submitted as well, which results in duplicated submissions and multiple e-mails being sent.
Steps to reproduce
1. Clean installation of eZ Platform EE 2.5.6
2. Properly configured swiftmailer.
3. Log in to the back office as an Admin, create a new Form Test Form with two fields: Single line and Button. Set Button action to display message "Sent!" and notification on e-mail. Publish it.
4. In ezplatform.yml set:
Replace <test_form_content_id> with Test Form Content ID.
5. Add Form Block to Home, select Test Form. Publish it.
6. Open Home in site SiteAccess.
7. Submit one of the forms.
Both Forms will be submitted - you will see two "Sent!" messages, there will be two entries in Submissions Tab for Test Forn and two e-mails sent.
Only a single Form is submitted.