A customer has been using the built-in POP3 Connector to collect some external accounts, bringing them in to the selected users. It is a very small company & there is no SMTP inbound used. The POP3 Connector has been running happily for several months - since they purchased the new server with it. Recently they were disconnected from the Internet via hardware fault and were without access for a week. The server is now back on line & experiences issues with the collection of the e-mails - sending continues to work.
Having been through the blog article on Technet, the crucial symptom I have pinned down is an Event 208: Timeout on the SMTP delivery side (POP3 Connector sending into the server via localhost:25).
"Event 208: The TCP/IP Connection with the 'localhost' server was terminated while trying to access the '<mailbox>' mailbox. The cause may be server problems, a long period of inactivity, a connection time limit, or incorrect connection settings."
Having turned on verbose logging on the POP3 Connector, I can confirm the symptom of sending the e-mail in (DATA exchange of SMTP delivery) completes as follows:
"[t 0] 11/19/10, 15:09:55: (SMTP) [TX]
[t 0] 11/19/10, 15:10:35: Timeout 'localhost' !!!!
[t 0] 11/19/10, 15:10:35: Failure hrResult (0x800ccc19) trying to deliver message id 2:
[t 0] 11/19/10, 15:10:35: (no server response)
[t 0] 11/19/10, 15:10:35: EVENT: The TCP/IP connection with the 'localhost' server was terminated with while trying to access the '' mailbox. The cause may be server problems, network problems, a long period of inactivity, a connection time limit, or incorrect connection settings.
[t 0] 11/19/10, 15:10:35: (AsyncConn [ localhost:25 ]) Connection to 'localhost' closed."
I can telnet to localhost:25 and send an e-mail manually - even delaying the conversation for longer than it takes for a "Retrieve Now" on the POP3 Connector to fail (i.e., start telnet session with localhost:25, EHLO, MAIL FROM, RCPT TO, DATA, start the Retrieve Now on the POP3 Connector and wait for it to fail, back at the telnet session complete the E-mail detail and finish with the . on a line by itself & the telnet e-mail is accepted).
Blog article already gone through with a fine-toothed comb: http://blogs.technet.com/b/sbs/archive/2009/07/01/sbs-2008-introducing-the-pop3-connector.aspx
Additional EE Q to ensure the timeout is higher than needed: http://www.experts-exchange.com/Software/Server_Software/Email_Servers/Exchange/Q_24398627.html
- both the accepted solution & the after-comment.
NB: I do not need any lectures about using the POP3 Connector! There's a good reason & if you don't agree with its use please simply don't answer.