How can I get a list of active Trello users?

[Wayne_Reilly]

I want to email all the people who are actively using Trello boards and cards. As all Atlassian users have Trello access but not all are using it I want to minimise the list of users to email to.

[G subramanyam]

Hi @Wayne_Reilly welcome to the Atlassian community.

While I didn't get your statement "As all Atlassian users have Trello access but not all are using it I want to minimise the list of users to email to", I believe you mean your organization/ project members. 

May I know if you have tried exporting data from Trello. Also, their are few marketplace plugins you can utilize. Please be noted, in-order to export all the boards in your Workspace, you need to have a Trello Premium.