This may sound a bit strange, but I need some suggestions of where to start looking. I have SBS 2008 installed which includes Exchange 2007. There is nothing special about the installation. Server is behind a modem and router. System/Network has been stable for over a year. That being said, tThe past several days I have noticed that my firewall has been turned off, after I have turned it on. (i.e. I went in and manually reset it to default settings, fire wall on, yesterday, and this morning it was off AGAIN). Then to add insult to injury, no mail has been received and customers are reporting that mail is being returned (reason: 452 4.3.1 Insufficient system resources) Rebooting the server seems to solve the mail issues for a while, but it limits my ability to leave the computer room. Mail best practices report a couple of not default settings but nothing that stop all inbound mail. Are these related and any suggestions where to look to fix it/them? ThanksTodd Williams

Could be back pressure, check your exch server event logs for event ID's of 1500x Could be that you have low disk space which is the most typical I have come across when dealing with back pressure. Sukh

Thanks for you suggestions. back pressure? "exch server" event logs? I have examined eventvwr/windows logs/application and dont find anything that looks related. I have examined eventvwr/applications and Services Logs and don't see anything that looks related. Might I be looking in the wrong place? low disk space? I wondered of that. C drive has 1GB+ free, D drive has 16GB + free. The mail store is located on the D drive. BTW, the "alert" for you reply did not come in, so I am kind of just monitoring this thread. And I have done some testing from other mail addresses and have confirmed that mail is not arriving. (Still waiting for error message to tell me that it can not deliver.) Yesterday I rebooted the server and a flood of mail arrived shortly after I did that. I could not replicate that experience today. HELPTodd Williams

Which veriosn of Exch ? Sp version? Rollup? I believe your low on disk space, 1GB is too low. What is the the total HD size. Try this, HD size * 0.04 = Free space you should have on the C: drive.Sukh

About Exchange Server 2007: Exchange Server 2007 Microsoft Corporation Version: 08.01.0436.000 Local Disk (c;) local disk total size 73.2 GB, free space 2.49 GB Data (d:) local disk total size 75.6 GB, fre space 43.6 GB. data files are: Name Database File Path Status Copy Status First Storage Group Disabled Mailbox Database D:\Program Files\Microsoft\Exchange Server\Mailbox\First Storage Group\Mailbox Database.edb Mounted Second Storage Group Disabled Public Folder Database D:\Program Files\Microsoft\Exchange Server\Mailbox\Second Storage Group\Public Folder Database.edb Mounted If the problem is space, what would jam up the C drive? TTodd Williams

could be anything, run a search using widows search for large files and see what file there are, sort by size and delete of not needed or find out what is causing them to be created. As a min, I'd free up about 5GB and see if you have the issue.Sukh

I will give that a try. I have been running with it below 5 GB for a long time. I notice that when I run the Best PracticesAnalyzer, one of the things flaged is: The value for the maximum Extensible Storage Engine (ESE) cache on server INDI has changed. Current maximum cache size is 500 MB. I followed the links, but all they want to talk about is Exchange 2003, and how to fix it in 2003. Do you know anything about the ESE cache? It seems that maybe it should be 2 BG? I don't know how it was changed or where to go to fix it. T Todd Williams

You can probably run it with around 2.92GB but I'd recommend that you have more than this.Sukh

You didn't say anything about ESE?Todd Williams

ESE Cache - http://technet.microsoft.com/en-us/library/bb691304(EXCHG.80).aspx - This shouldn;t be set not recommend setting a maximum size for the database cache. The maximum database cache size should not be lower than the minimum recommended amount of physical RAM. If you must reduce the maximum database cache to below the recommended levels, you should simultaneouslySukh

Well, I seem to be making progress. I have restarted the server several times today, without effect. But this time I changed the ESE Cache (thank you for the link) and this time I started to get some mail. So I would like to leave this OPEN until tomorrow to see if everything continues to work. Thank you for your assistance!Todd Williams