How do I include the e-mail address when importing users from tomcat-users ?

Have you tried repotools -exportUsers and the reverse operation -importUsers?

If you just bring over the tomcat-users file that only fixes the authentication and repository groups. From simply looking at the tomcat-users.xml you can see that the file does not store the e-mail information (or licenses etc). That information is stored in the JTS and other databases. The repotools-jts with export and import the users should fix that.