Rt-mailgate not relpying to new tickets via email

Hello all,

We are running RT 3.4, having recently upgraded from 3.3, on Debian
testing. I noticed yesterday that the auto response emails to newly
created tickets are not being sent out. Tickets are ending up in the
correct queues, with the correct requester name, and in the ticket
history, RT has a note saying that the email has been sent. Admin CC’s
of the relevant queues are receiving emails to say that a new ticket has
come in.

These lines appear in the log file:

Jun 13 15:11:13 server RT:
rt-3.4.4-22362-1150207873-1178.3948-2-0@domain.ac.uk #3948/25217 -
Scrip 2 Autoreply on
Create (/usr/share/request-tracker3.4/lib/RT/Action/SendEmail.pm:237)
Jun 13 15:11:13 server postfix/sendmail[26477]: fatal: No recipient
addresses found in message header
Jun 13 15:11:14 server RT: About to think about scrips for transaction
Jun 13 15:11:14 server RT:
rt-3.4.4-22362-1150207873-1178.3948-2-0@domain.ac.uk sent To:
client@client.com Cc: Bc
c: (/usr/share/request-tracker3.4/lib/RT/Action/SendEmail.pm:297)

While searching for answers, the only thing I have found that relates to
my problem is that I am missing the “-t” option from the script that
reads the header. I assumed that this would be in rt-mailgate (but I am
new to RT and am likely to be wrong) and it is not there.

Can anyone help / point me in the right direction?