Help with RT 3.0.11 support queue

Hi
I have been using RT for more than 1 year now and suddenly its giving me
a problem
The default setting was that when someone sends a mail to
support@mydomain.co.ke, it autoreplies and creates a new ticket, but
this has stopped working now all of a sudden
The queue for support has not had any changes and not has the mailserver
that receives mail, there is no firewall set also
However, when a ticket is created from within the RT system in the
support queue, a mail is generated and sent to the requester and other
parties
Please help.

Regards,

Bhavesh Mistry