[exim] Batch SMTP hangs

Hi,

I have a perl script that runs as a pipe transport and injects two
e-mails back into the system via BSMTP. Up until a recent upgrade from
Woody to Sarge this all worked fine. Now, when injecting the second
message, my script hangs when closing the file descriptor to exim. The
perl looks something like this:

    open BSMTP , "| /usr/sbin/exim -oMr foo -bS" or die "Unable to run exim: $!\n";
    print BSMTP "MAIL FROM:<$from>\n";
    print BSMTP "RCPT TO:<$to>\n";
    print BSMTP "DATA\n";

    # print out body

    print BSMTP ".\n";
    close BSMTP;
    die "Exim BSMTP failed, code $?\n" if ($?);

Exim (version 4.51) does accept and queue the message. I've generated
some debug and the last few lines of debug are:

    calling local_scan(); timeout=300
    local_scan() returned 0 NULL
    Writing spool header file
    Size of headers = 334
    LOG: MAIN
      <= <<<log entry>>>
    search_tidyup called
    smtp_setup_msg entered

There would normally be another line
    search_tidyup called
and then the process terminating.

I'm not sure how to continue to debug this, so any advice would be appreciated.

regards,
John