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Error 450 sending internal mail

Posted on 2016-11-21
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Last Modified: 2016-11-29
Exchange 2010 SP3 RU15, single CAS, 2 DAGs. Receive connector configured to receive internal messages from our voicemail server to relay to the internal users mailbox who received a voicemail. Connector had been working up until about 2 weeks ago.

When attempting to send a message via telnet from the voicemail server I receive a message at the RCPT TO stage stating "450 too many connections from your IP (rate controlled)"

The connector had the MaxInboundConnectionPerSource orignally set at 50, changed to 500, restarted the Transport Services service and the issue still persists.

No recent changes made to the network or the servers. Any ideas where to look next?
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Question by:Lee James
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Expert Comment

by:Justin Moore
ID: 41896267
Try restarting the "System Attendant" if that doesn't try the "Information Store". The second one will briefly disconnect everyone for the period of the restart. If those two don't work you know you your limits need to be changed elsewhere.
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Jason Crawford earned 250 total points
ID: 41896278
That doesn't look like an error generated by an Exchange server.  I know you said it was internal, but do you have a firewall or spam filtering appliance in between the voicemail appliance and the end user?
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Author Comment

by:Lee James
ID: 41896297
There are no firewalls or spam filtering appliances in between. Restarting the services will have to wait until after hours later this evening.
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Expert Comment

by:Jason Crawford
ID: 41896318
If  you haven't already done so, enable verbose logging on all Receive Connectors:

Get-ReceiveConnector | Set-ReceiveConnector -ProtocolLoggingLevel Verbose

Open in new window


After enabling verbose logging, send another email via the voicemail appliance.  Give it a few minutes and check the most recent SMTPReceive log located here - C:\Program Files\Microsoft\Exchange Server\V14\TransportRoles\Logs\ProtocolLog\SmtpReceive.  Open the .log file and search for the recipient address.
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Assisted Solution

by:Justin Moore
Justin Moore earned 250 total points
ID: 41896385
I think Jason's right, 450 is not an Exchange error but a Telnet error your seeing. Telnet is quirky at best. Sometimes just hitting the backspace key can cause a failure. I would be cautious when going down that path to focus on the 450 error. you may end up troubleshooting two different problems. The fact that the voicemail stuff was working and then stopped means that MaxInboundConnectionPerSource isn't the issue either. I would check and make sure you don't have a hung service and I would check your logs and make sure you don't have a DNS issue somewhere. A lot of times we make small minute changes that don't seem relevant and we forget about or even MS Updates can snowball into unseen issues.
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Author Closing Comment

by:Lee James
ID: 41905650
Routing issue was the root cause. Thanks for the assistance.
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