What is the initial action you should take for legacy accounts when preparing for a Slack migration?

When preparing for a Slack migration involving legacy accounts, the most effective initial action is to merge user emails and roles. This step is crucial because it allows for a streamlined transition where users maintain their identities and histories within Slack. By merging user accounts, you can ensure that each user has a unique identity that reflects their role in the organization and avoids complications that arise from duplicate accounts.

This process also helps in preserving user data, such as messages and files, which is essential for continuity during the migration. Maintaining consistent email addresses and roles facilitates easier permissions management and access control once the migration to the new environment is complete.

In contrast, upgrading all legacy accounts to paid accounts could lead to unnecessary costs without any immediate benefit and may complicate the migration process if not all users require similar functionalities. Deactivating old accounts might lead to loss of historical data that could be important for team collaboration and reference. Creating new accounts for all users would unnecessarily complicate user management, as it could result in loss of data associated with the legacy accounts. Thus, merging user emails and roles stands out as the optimal first action in the migration preparation process.