We had fresh install of Exchange 2013 CU3 and found that the clients weren’t able to connect to exchange server over IMAP protocol. Telnet to the name and Ip of Exchange server on port TCP 143 (IMAP Port) was also failing.

Imap profile on outlook client was failing with following error

Log onto incoming mail server (IMAP): Your Server unexpectedly terminated the connection. Possible causes include server problems, network problems, or a long period of inactivity.

Strangely if we telnet localhost ( on port TCP 143, than we do get the IMAP Banner. Though  if we telnet locally on Exchange server to FQDN or IP address of Exchange Server; the connection fails.

Checked Application logs and found the following events

Event  ID 1011:
      Log Name:      Application

Source:        MSExchangeIMAP4
 Event ID:      1011

Level:         Information
User:          N/A

Computer:      SERVERNAME

The IMAP4 server’s Online status has changed to False

Checked the servercomponenthealthstatus and found it was offline:
RunspaceId                 : 
PSShowComputerName         : False
SerializationData          : }
ServerFqdn                 : SERVERNAME
Component                  : ImapProxy
State                      : Inactive
ServerWideOfflineIsOffline : False
RemoteStates               : {}
LocalStates                : {Microsoft.Exchange.Data.Directory.Management.ServerComponentStatePresentationObject+RequesterDetails}
Identity                   : SERVERNAME
IsValid                    : True
ObjectState                : New


Further investigation revealed Server Component “IMAPProxy” was in Inactive state.

Executed the following command to fix the issue

Set-ServerComponentState -Identity SERVERNAME -State Active -Requester HealthAPI -Component ImapProxy

Restarted the IMAP services

This resolved the issue for us and hopefully for you too.  Feel free to start a new thread in our forum if you need further assistance.

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An automobile enthusiast at heart and computer geek by profession, started my Career with MS in 2005.Left Jobs and started Pledge Technologies (the parent company to Grishbi) back in 2009.We have been providing IT consulting to various Small and Medium businesses across US and UK since then.Our company specialises in Microsoft Server technologies like AD, Exchange, the rest and with numerous Office 365 migrations under our belt, we quite an expert with that too. Whatever we learn in our day to day life, we share it back on Grishbi as a Thank for all the love and support our customers have given us.
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