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Misssing emails - SBS/Exchange 2003

We're seeing an intermittent issue where sometimes emails with attachments are not arriving on the server.

We use an external email scanning solution that is showing the emails as delivered and I've spoken with the support guys for that system that have checked and have said everything is ok there.

On the external system we can redeliver the emails and when doing this they arrive ok so doesn't appear to be an issue with size restrictions on the server.

It's an intermittent issue but one that is hard to track down. Any suggestions?
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Plaice
Asked:
Plaice
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1 Solution
 
Brian BIndependant Technology ProfessionalCommented:
If you have antivirus scanning you mail I have found sometime the size of the attachment slows the delivery process down enough that it "times out" and doesn't deliver. If that is the case, you could try changing your size limits, either on the AV program, or in Exchange to only permit attachments small enough to pass the scan.
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PlaiceAuthor Commented:
There's AV on the server but it does not scan the incoming mail.
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Brian BIndependant Technology ProfessionalCommented:
Okay, first idea didn't work. Idea #2....

So if I understand the emails are making into the "external system". Some sort of external anti-spam service? If they are arriving at that point, but not getting to your server, then the answer lies in the logs of the external system. Those logs will tell you why the messages didn't get delivered. You'll have to push the support people to get this since it sounds like they are finger pointing. However its really hard for you to show something never arrived on your end, but its easier for them to show that it wasn't delivered.
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PlaiceAuthor Commented:
You're right, it is an external anti-spam service.

They were my first point of call and their logs are showing the emails as delivered.
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Brian BIndependant Technology ProfessionalCommented:
Could have sworn I wrote this yesterday, but anyway...

The next step then is to look up the message tracking in Exchange Manager and see where the messages went. Perhaps they went into junk mail by accident.
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PlaiceAuthor Commented:
See that's the thing, the messages are not showing in message tracking. Only when we've resent them from the external system.
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Brian BIndependant Technology ProfessionalCommented:
You are right, that is odd.

Would it be possible to set one/all of the mailboxes to automatically copy another address? That will tell us if the mail is getting to the correct queues on the server.
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PlaiceAuthor Commented:
Sorry don't understand what you mean?
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Brian BIndependant Technology ProfessionalCommented:
In the user's account you can specify that the mail be sent to another address as well as the original. If the alternate addess receives the message, this will tell us if the problem is the junk filter.

Incidentally, check the users mailbox and see if they have any rules that could be affecting this.
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PlaiceAuthor Commented:
Well if the problem was the junk filter then the message wouldn't work when it was resent from the external anti-spam solution?

Also when the email does not arrive and there are more then one user CCed then all users do not receive the email. When redelivery is attempted it works.

The only issue with redelivery is it has to be done to one user at a time. Could it be an issue when there are multiple users CCed to the same mail? It only seems that emails go missing when this happens eg, attachment with multiple users CCed.
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Brian BIndependant Technology ProfessionalCommented:
I took a step back and looked at this from the beginning again and here's what I thought was strange...

Normally an external service will either hold or deliver messages. If a message is in the "held mail" in the external service, that means it was never delivered. So if the "failed" messages are still being held externally then the problem can't be any sort of setting on your server because the message never got there.

So forgetting about the problem messages for a minute... Can you go back to the service and tell it do re-deliver *any* message? Even if it was successful the first time? If not, then the key to the problem (but not neccessarily the fault) lies in the logs on the external service. We aren't trying to blame them, but perhaps that's why they aren't being forthcoming with the information.

The other thing you should probably check is your firewall... Make sure that the IP the service uses to deliver the mail is whitelisted from any sort of checks your firewall might be doing. If possible, you also might check your firewalls logs for evidence of any delivery attempts of the failed messages. The external support people might be able to tell you the exact time if you need to narrow things down. However, if your firewall is not showing any traffic originating from the mail delivery service at that time, then the problem definitely lies with the external service, since no traffic means they never attempted to send it.
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PlaiceAuthor Commented:
Yes we can redeliver any message that has passed through the external system regardless of whether it was delivered or not. Even if the message was flagged as spam and not delivered we can choose to deliver the email. It's a very good system, and one I've used in the past, and never seen an issue like this which leads me to believe the issue does not lie there.

I'll check out the firewall and get back with a response.
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Brian BIndependant Technology ProfessionalCommented:
Thanks. Okay, since you can redeliver any message, my third paragraph in the previous message is not relevant.

So the logs are the next item. Please let me know.
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PlaiceAuthor Commented:
Well there was nothing in the logs on the firewall. Thanks for the help TBone, will give you the credit but think we'll leave this one until it happens again.
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PlaiceAuthor Commented:
Giving credit for the help.
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