E-Mail-Response does only work partially

After the installation of OSTicket I managed to configur automatic responses,

BUT:

- when the customer enters an new ticket he does not get an E-Mail with ID and everything

- when I write an answer in OSTicket he gets an E-Mail

So the email-config itself seems to work, but WHEN the user should get it is wrong. Sombody knows what I did wrong?

Thanks and greets

Irene