Is someone else having problem with this odd thing called SBS 2008
pop3connector?
Many clients that use this connector are telling us that, for some reason,
it is considering XMail´s headers as invalid.
Some information from Microsoft´s site:
Email Rejected Due to Protocol Errors (Invalid Headers)
Note: A long-term solution to this issue is being investigated
[New Content courtesy of Dan Thompson]
Exchange will close an SMTP connection after a certain number of protocol
errors (5 by default). (see the MaxProtocolErrors property of the
ReceiveConnector object at:
http://technet.microsoft.com/en-us/library/aa998618.aspx)
When the SBS 2008 pop3connector downloads a message from a POP3 mailbox, it
needs to figure out what the return path for the mail should be, which it
does by reading the email's headers. The pop3connector does not do
validation of the header value--it lets Exchange take care of that. If the
header value that the pop3connector chooses is malformed, when it is sent to
the Exchange server (as part of the MAIL FROM command), Exchange will
reject it with a 501 error. That counts as a protocol error, and therefore
is counted against the MaxProtocolErrors limit. Since the pop3connector was
not able to deliver the mail, and does not know if the mail is safe to
delete, it leaves the mail on the POP3 server.
If there are 5 of these messages in your POP3 mailbox, then there will be 5
protocol errors in the pop3connector's SMTP session, which hits the limit,
and Exchange will end the session with a transient error (4xx). When this
happens, the pop3connector recognizes that the error is transient, and will
retry again at the next scheduled download period. But since those 5
malformed messages are still in the POP3 mailbox, the same thing will
continue to happen, with no forward progress being made.
The workaround is to increase the MaxProtocolErrors property of the
Windows SBS Fax Sharepoint Receive connector, and then restart the Exchange
Transport service for the change to take effect (and you'll have to restart
the pop3connector service, too, since it depends on the Exchange Transport
service). Unfortunately, you can't set that property from the Exchange
management GUI, so you have to do it from an (elevated) Exchange Powershell
prompt. Here are the instructions:
From an elevated Exchange Management Shell (Exchange Powershell window)
(right click on Start--Microsoft Exchange Server 2007--Exchange
Management Shell and then choose Run as administrator) run the following
Powershell commands:
Set-ReceiveConnector -Identity ($Env:computername + \Windows SBS Fax
Sharepoint Receive + $Env:computername) -MaxProtocolErrors 500
Stop-Service pop3connector
Restart-Service -force MSExchangeTransportStart-Service pop3connector
That will increase the MaxProtocol errors (of the internal receive connector
only) to match the pop3connector's max emails downloaded per session. Once
you get 500 messages with malformed headers stacked up in the POP3 mailbox,
though, you'll still have to delete them manually.
Regards
Edinilson
:-
ATINET-Professional Web Hosting
Tel Voz: (0xx11) 4412-0876
http://www.atinet.com.br
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