Managed users got removed email from email service

[Casian Gabriel]

Hello,
I use a free Jira dashboard for my company tickets. We try to use it as much as possible, because we are actually a window factory, not quite an IT company. That's why I used mail.com to create free emails for my sales agents, in order to make the process of adding them on Jira smoother. 
The issue is that those emails were not used since then, so they got removed by mail provider. Now I can login only with few users (whose emails account are more recent), but the big issue is that I cannot access anymore even the "admin" account, because if I want to log in in Jira, it request a validation code from email. So now I'm blocked in a loop, if I want to access Jira I need to access my deleted email accounts. I don't want to delete all that users from team and to create new ones in their place, because we have quite a lot tickets assigned to them.
Have you been in such situation? What can I do?