[EXIM] exit/return value for quota-overflow?

Hi,
I wrote a transport:
sqluser_pipe:
driver = pipe
command = "/usr/local/sbin/exim-informix ${local_part} ${domain}"
user = informix
group = informix

Is there any returncode/exitcode to let Exim know that a mail is
rejected because of a quota overflow (like the quota-option for 
appendfile)? Or is the only way to mail it back manually?
Thx
    Lars

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