Yesterday I could change my own email, today I can't and I cannot change other peoples either. I am an administrator with the highest permissions.

We cannot be in a situation where by we cannot change email addresses. We recently changed company name and therefore as such the email addresses need updating. We cannot create new users for these people because we need the paper trail on JIRA tickets/confluence docs of approvals, comments, discussions etc and I do not want those changing to 'Former user'.
Please help?
Thanks