How to suspend one job and execute another job with a single Unattended license then resume it again automatically?

Hi All,
We have a strange situation with one of our clients. We had developed a process (Update AD user expiry date based on the details fetched from a ticketing tool) and deployed it in production.

Now client wants to do an enhancement : Client doesn’t want us to schedule the process. The above process needs to be triggered whenever a Ticket Mail is available in local outlook. Bot needs to monitor the mailbox 24/7 and trigger the actual process if there is mail. Continue the mail box monitoring otherwise. They don’t want us to touch the existing process and Mail trigger enhancement needs to be done with a separate process. How can I achieve this with only 1 unattended license?

We have a lot of restrictions, not to run PS scripts, bat files etc. Need to achieve this completely based on UiPath capabilities. Can any one help me for a solution?