How to map users between products hosted and atlassian cloud ?

[Deleted user]

Hi there !

We are currently trying to migrate our Jira and Confluence self-hosted installations to Atlassian Cloud products.

We started by importing one Confluence space but we saw that for each objects when we are on the "Page information" page all changes were made by some "Unknown User" with an ID. 

Is there a way to stick with user email as all out current user will use Atlassian Cloud products and we want them to be able to retrieve all of their files ?

We have the same types of interrogations regarding our Jira migration : how it will affect users ? Could we have some mapping based on email ?

Thanks !

Saâd