[otrs] Agents don't receive notification emails for tickets posted in their queues

I know this has been discussed many times, but I can't figure out a solution to this problem even after having browsed all the related messages in this mailing list. In my otrs 4 (patch level 5), installed on ubuntu server 14.04, when an agent posts a new ticket in a queue, the other agents subscribed to the same queue don't receive the notification email. All the agents have the correct queue selected in "my queues", all their notifications options are set to "yes", there's no event defined in Notifications(Event). When the agent posts the ticket, in the log I get only these two lines: Feb 13 10:36:03 srvapp2 OTRS-CGI-63[1857]: [Info][Kernel::System::Ticket::TicketCreate] New Ticket [2015021363000013/Ticket di test ] created (TicketID=13,Queue=ICT,Priority=3 normal,State=open) Feb 13 10:36:06 srvapp2 OTRS-CGI-63[1857]: [Info][Kernel::System::Ticket::Article::ArticleSend] Sent email to '"Test Customer" ' from 'OTRS System '. HistoryType => EmailAgent, Subject => [Ticket#2015021363000013] Ticket di test 10; As it can be seen from the log, an email is correctly sent and received by the customer for which the ticket is created, but no emails are sent to the related agents. Is there anything else I can do? What are the source code files where agent notification is handled? I might try some debugging if everything else fails. - Fabrizio