Webform Email Reply Threads
This module adds threaded email conversations to webform replies. When a webform is submitted or replied to, an email is sent with a link to view and continue the conversation on the Drupal site.
Provides threaded email messaging for webform replies.
Quick start
Set up a thread type for each webform that you'd like to have reply threading functionality. You can find this under the webform's Settings > Threads tab, or in the administrative menu. Here you can toggle the active state of threading functionality for the webform, as well as the active state and copy sent in notifications.
You'll likely want to create a thread for each submission, so go to the webform's Settings > Emails/Handlers tab and add a "Thread create" handler. Here you'll configure the thread's initial sender and recipients, utilizing whatever values you would like including tokens from webform submissions.
When submissions are created and/or replied to (depending on your setup) emails are sent to the sender and recipients which include links to the Drupal site where the user may view and reply to the thread.