Spark 2.0 is the new version of the popular email client created by Readdle which has collaborative features to work with your team together on emails.
The users can share a draft with the team by means of private chat conversation below the Compose button. It works like Google Docs where the users can write and edit emails at the same time.
Spark also allows their users to create links of emails or threads that they can share to any other messaging app that will directly connect the team member to the particular conversation. It has permission controls to be set to make sure that only specific people can access the particular emails.
It is now available for iPhone, iPad and Mac. The new version will be free for the existing Spark users.