Therefore, to transfer all the Emails and Attachments, it is recommended to take into account migration tips mentioned in this article.
You have to fill in API keys for every user in Migration Wizard to migrate automatically from Pipedrive whole data related to different users.
If not, only a part of the records will be transferred.
To be exact, the service will move automatically only those Emails and Attachments that are related to the user/users who's API key was/were entered for the transfer.
So, do not forget to enter API keys for every Pipedrive user you wish to migrate.