When the file system error occurs, &fml8; exit abnormally to make MTA re-deliver the message again to &fml8; or &fml8; re-delivers it by itself without saving the article on the file system. So &fml8; do not lost received messages whereas both log or summary file lack something. Describe below what happans when the file system error occurs in the delivery process. &fml8; reads a message and writes it into the disk once. If succeeded, it processes more. If failed, &fml8; exits abnormally as exit(EX_TEMPFAIL) for MTA to re-deliver it. See for more details. In this case, incoming message queue may have a incomplete message. &fml8; tries to remove it in abnormal exit. Even if failed, the queue management system removes it later. In normal case, &fml8; updates the article sequence number and re-reads it and compares it again. If the check fails, &fml8; exit(EX_TEMPFAIL) for MTA to re-deliver it. The article sequence number updated. After that, &fml8; does not do exit(EX_TEMPFAIL) to deliver the message on memory as could as possible. In this stage, the article sequence has been updated. In this case, &fml8; does not create a new article file but the original message is already on the disk. The header of the article differs from the original one but the body content is same. So &fml8; tries to link(2) the original mail in the incoming queue to the article file to save the content. If it could be, it is useful to implement another command which fixes the article header later. It is not implemented. &fml8; tries to deliver the message on memory. If the delivery process exits abnormally, distribution of article ends incompletely since &fml8; can not use outgoing queue due to file system error. &fml8; saves the message into the outgoing queue, after succeeded, the delivery process runs. When &fml8; fails to write the outgoing queue, &fml8; exits incompletely. See for more details.