I have a SBS server 2008 with Exchange and the useres reported that they were no longer receiving email.
I investigated and found the cause most likely to be the Back Pressure issue. I edited edgetransport.exe.config to chance the monitoring line to false, then proceeded to clean up the C: drive (mostly old log files) to fre up space.
After editing the file the edgetransport service refused to start so i restored the backup file and it still refused to start.
Following a tip off technet i changed the account the service ran under to the local system account and the service started but users are still not receiving email and they can no longer send out as well.
Checking the logs the only error i could find was error 12014.
Any help would be greatly appreciated.