Problem injecting larger messages

Hi,

I am using qmail-queue to inject messages into tmda via tmda-inject as 
follows:

exec /usr/bin/qmail-qfilter /var/qmail/bin/qmail-queue-tmda1

(Though there are some other scripts to take care of the environment 
variables...)

This works fine, except, if I want to send emails with attachments. 
Presumably because they are larger. I am finding the following im my 
qmail smtpd log:

2006-10-10 20:44:44.807173500 Traceback (most recent call last):
2006-10-10 20:44:44.812243500   File "/usr/bin/tmda-inject", line 141, in ?
2006-10-10 20:44:44.817147500     orig_msgout_as_string = 
Util.msg_as_string(msgout)
2006-10-10 20:44:44.817682500   File 
"/usr/lib/python2.4/site-packages/TMDA/Util.py", line 560, in msg_as_string
2006-10-10 20:44:44.818171500     g.flatten(msg, unixfrom=unixfrom)
2006-10-10 20:44:44.818501500   File 
"/usr/lib/python2.4/site-packages/TMDA/pythonlib/email/Generator.py", 
line 103, in flatten
2006-10-10 20:44:44.818819500     self._write(msg)
2006-10-10 20:44:44.819127500   File 
"/usr/lib/python2.4/site-packages/TMDA/pythonlib/email/Generator.py", 
line 141, in _write
2006-10-10 20:44:44.819454500     self._fp.write(sfp.getvalue())
2006-10-10 20:44:44.819769500 MemoryError

I guess the memory error means that tmda has run out of memory. Is this 
really the fact, and if yes, how do I remedy the problem?

Thanks in advance for the help.

Regards,
Arik