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Randomly not receiving mail

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Randomly not receiving mail - 18.Aug.2008 12:56:59 AM

MattC

Posts: 21
Joined: 28.Jul.2008
Status: offline

Here is the setup
Exchange 2007 SP1 - Mailbox, CAS, HT installed on this one and only Exchange box
Windows 2008
Domain is in 2000 native mode, 2 DC's, 1 domain
Watchguard firewall in place with latest firmware updates

The problem is as follows.
This was a migration from Exchange 2003 to 2007. 2003 has now been removed from the environment.
Since E2k7 was installed there has randomly been loses or delay's in mail delivery. At first I thought that there may be an issue with the max number of allowed inbound connection to E2k7 as this client is getting around 10,000 spam mails a day and they are all being delivered to the E2k7 box after being identified as spam by the firewall (spam assasin is being used to append the subject of spam and then deliver it to E2k7). I have turned NDR's off to reduce mail traffic from all these spam messages
This server had NIC teaming on, the team has now been disolved for testing, latest Proliant Support pack 8.1 for win2k8 x64 has been install to make sure that all drivers are upto date.
Queue's on Exchange are always below 10
Any one have any idea's?
I feel like I am bashing my head against a wall at the moment as I can't see why there is a delay/loss in mail messages.

Post #: 1

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RE: Randomly not receiving mail - 18.Aug.2008 1:48:54 AM

TXB2

Posts: 53
Joined: 20.Mar.2008
Status: offline

Hi,
You'll need to switch NDRs back on if you want to troubleshoot this properly. If there is a delievery problem then we need to know about. Use the message tracker (under the toolbox of the EMC) to find out what's happened to your "missing" emails.

Regarding your spam: I don't think its a good idea to simply stamp the subject header and accept delivery. Thats alot of unwanted emails flooding into your enterprise. You should be rejecting the bulk of it at the perimeter.

Cheers,
TXB2

(in reply to MattC)

Post #: 2

RE: Randomly not receiving mail - 18.Aug.2008 2:32:47 AM

MattC

Posts: 21
Joined: 28.Jul.2008
Status: offline

I agree that they shouldn't be getting into the Internal network but unfortunately this is a client site. I have had this discussion with them already and explained the benefits of blocking spam at the DMZ.
As far as NDR's go the senders are getting
Your message did not reach some or all of the intended recipients.

Subject: RE: test Sent: 15/08/2008 3:13 PM
The following recipient(s) could not be reached:

commander on 17/08/2008 3:26 PM
Could not deliver the message in the time limit specified. Please retry or contact your administrator.
<xyz.com.au #4.4.7>
I have been through the message tracker and I can only find messages that have actually been delivered, so I am fairly certain that there is not an issue with HT->Mailbox/Database transfers
The messages do not even seem to be hitting exchange, as if there was a problem there would be NDR's and there were no NDR's being delivered (before I turned NDR's off I checked this)

(in reply to TXB2)

Post #: 3

RE: Randomly not receiving mail - 18.Aug.2008 2:41:31 AM

TXB2

Posts: 53
Joined: 20.Mar.2008
Status: offline

Have you used the mailflow troubleshooter using the DSN code 4.4.7?
Sounds like a problem from your FW to the Exchange server but running the mailflow troubleshooter should direct you closer to the source of the problem.

Cheers,
TXB2

(in reply to MattC)

Post #: 4

RE: Randomly not receiving mail - 18.Aug.2008 2:57:29 AM

TXB2

Posts: 53
Joined: 20.Mar.2008
Status: offline

One more thing - I'm not familar with Watchguard but if it has some sort of SMTP proxying feature running then disable it whilst you are going through the troubleshooting process.

(in reply to TXB2)

Post #: 5

RE: Randomly not receiving mail - 18.Aug.2008 4:57:35 AM

MattC

Posts: 21
Joined: 28.Jul.2008
Status: offline

I am going to disable watchguards spam component and enable the HT anti-spam component and see if it is something that the firewall is doing to the messages that may be causing Exchange to drop the message because it see's it as malformed message. I know I am clutching at straws here but it's all I've got
I ran the Message Tracking Troubleshooter and there were no errors.

(in reply to TXB2)

Post #: 6