Redmine

I have redmine 3.2.0 placed on localserver2:

Environment:
  Redmine version                3.2.0.stable
  Ruby version                   2.0.0-p647 (2015-08-18) [i386-mingw32]
  Rails version                  4.2.5
  Environment                    production
  Database adapter               Mysql2
SCM:
  Filesystem                     
Redmine plugins:
  no plugin installed

When somebody write an email to redmine (via exchange account) there is issue that every person have to wait some time for approach an incident in redmine.
What is the problem? How to accelerate this? I want to send incident to redmine then redmine creates a new incident in database. I've searched many topics but there're no solution. This issue only appears when user send incident via e-mail, when do it via browser - redmine makes incident instantly, so i want the same for e-mail way? Any suggestions how to change it or improve it?
Version internal problem or Ruby internal problem or Rails internal problem? I don't have idea. Please help.
For example when you send issue via e-mail to redmine at 10 o'clock sometimes you have to wait even 2 hours to see your incident via browser(after 2 hours you get also notification from creation)