Unfortunately the information you provided here is insufficient for us to diagnose the issue. I suggest opening a support ticket so we can collect more sensitive information to diagnose this issue.

I can give you all info you need.

The flow is that : 

- we received an email from flx14ea5e@scania.it that creates a ticket

-Smartertrack try to send the notification (auto-responder)

-this addresses can't receive emails, so generate this mail back 

-this mail come into Smartertrack and go inside the ticket with that message

- Smartertrack try again to send the notification... every 1-2 minutes (I expected that this retry should be done only few times)... creating an infinite loop

Hi, Emanuele

For the Email settings, do you have this box checked on the Options tab: Filter duplicate incoming emails? If so, that should keep an autoresponder loop from creating multiple tickets or ticket replies. 

Yes,

I have both selected.

Emanuele,

In the screenshot you initially provided, every visible bounce comment appears to have been created within the same minute. To diagnose this, we would need to be able to see the raw content associated with several of these bounce messages, as well as review the general history of the ticket. It would also be helpful to be able to review the logs from the affected time period. We do not ask for this information through community threads, in case there is sensitive data involved. This is why we suggested, and still believe, a support ticket is the best way for us to be able to resolve your issue.