Redmine

Hello everyone. First of all congratulate you on the amazing Redmine project.

I have found a situation that I do not know how to solve or if it has a solution in the current version, I'll tell you.

In my company I have been asked to mount the Redmine server.
I have configured the server, the email notifier and a mail inbox to create requests and replies.

All this part I have not had problems and it is configured.

But we have a costumer who is also using Redmine and this situation occurs.

If costumer creates a request for example with id #120, to my Redmine a notification comes with the following subject [XXXX # 120] so that our mail handler can create the request.
As in my system the issue #120 is not created yet, Redmine thinks that it is a response to an existing issue in my system but when not finding the issue by id, do not create it.

I've been looking for the code app / models / mailhandler.rb and looking for the function "receive_issue_reply"

def receive_issue_reply (issue_id, from_journal = nil)
    issue = Issue.find_by_id (issue_id)
    return unless issue
    # check permission
    unless handler_options [: no_permission_check]
      unless user.allowed_to? (: add_issue_notes, issue.project) ||
               user.allowed_to? (: edit_issues, issue.project)
        raise UnauthorizedAction
      end
    end

I notice if the id of the issue does not exist, it does not create the issue.

My question is this:
Can Redmine collaborate with another Redmine system to create issues through email?
How can you synchronize the ids of my local issue and of the remote issue?

Thank you very much,