--- libexec/dma/dma.c.orig	2009-02-09 01:36:50.000000000 +0100

+++ libexec/dma/dma.c	2009-07-04 00:12:53.000000000 +0200

@@ -612,6 +612,7 @@

 	const char *errmsg = "unknown bounce reason";

 	struct timeval now;

 	struct stat st;

+	struct flock fl;

 	syslog(LOG_INFO, "%s: mail from=<%s> to=<%s>",

 	       it->queueid, it->sender, it->addr);

@@ -620,11 +621,27 @@

 	syslog(LOG_INFO, "%s: trying delivery",

 	       it->queueid);

+	bzero(&fl, sizeof(fl));

+	fl.l_type = F_WRLCK;

+	fl.l_whence = SEEK_SET;

+	if (fcntl(fileno(it->queuef), F_SETLKW, &fl) == -1) {

+		syslog(LOG_ERR, "%s: failed to lock queue file: %m",

+				it->queueid);

+	}

+

 	if (it->remote)

 		error = deliver_remote(it, &errmsg);

 	else

 		error = deliver_local(it, &errmsg);

+	bzero(&fl, sizeof(fl));

+	fl.l_type = F_UNLCK;

+	fl.l_whence = SEEK_SET;

+	if (fcntl(fileno(it->queuef), F_SETLKW, &fl) == -1) {

+		syslog(LOG_ERR, "%s: failed to unlock queue file: %m",

+				it->queueid);

+	}

+

 	switch (error) {

 	case 0:

 		unlink(it->queuefn);