MboxMailRepository throws NPE when storing mail with mail from: <>

Here is the Stacktrace:

07/10/06 13:25:20 INFO mailetpackages.LocalDelivery: Error while storing mail.
java.lang.NullPointerException
at org.apache.james.mailrepository.MBoxMailRepository.store(MBoxMailRepo
sitory.java:518)
at org.apache.james.transport.mailets.ToMultiRepository.storeMail(ToMult
iRepository.java:230)
at org.apache.james.transport.mailets.ToMultiRepository.service(ToMultiR
epository.java:154)
at org.apache.james.transport.mailets.LocalDelivery.service(LocalDeliver
y.java:69)
at org.apache.james.transport.LinearProcessor.service(LinearProcessor.ja
va:452)
at org.apache.james.transport.StateAwareProcessorList.service(StateAware
ProcessorList.java:167)
at org.apache.james.transport.JamesSpoolManager.run(JamesSpoolManager.ja
va:203)
at java.lang.Thread.run(Thread.java:595)