Exchange RPC/HTTP aka Outlook Anywhere Troubleshooting

Outlook Anywhere (RPC/HTTP in Exchange 2003) is very useful and secured feature in Exchange. It requires careful planning and understanding. Outlook 2003/2007 may have trouble connecting with Exchange server via RPC/HTTP for many reasons.

I am assuming you already have the infrastructure ready. Let first understand what’s the Outlook setup looks like and what it means.

On fast networks: connect using HTTP first, then connect using TCP/IP

If Outlook detects a fast connection, that is >128,
        Try the FIRST attempt using TCP/IP (usual RPC session) to Exchange Mailbox server
        Then fail over to HTTP (RPC over HTTP) to the RPC Proxy server on further attempts

The fast connection by default is >128, set at the Network Card configuration. I am not sure how to change this value. I am sure it can be changed in Registry.

On slow networks, connect using HTTP first, then connect using TCP/IP

If Outlook detects a slow connection, that is <=128,
         Try the first attempt using HTTP to the RPC proxy server
         Then fail over to TCP/IP to Exchange mailbox server on further attempts

Now the troubleshooting the issues.

Outlook is not connecting to the Exchange server. (Connection Errors, "Disconnected" status)

Outlook Anywhere (RPC/HTTP) requires reliable Internet connectivity. If the computer has spotty wireless connection or busy Internet connection, Outlook will not connect. 

Solution: Make sure you have good wireless reception and check you can browse Internet. Try your Outlook Web Access in your browser. Are using "Use automatic configuration script" setting in Control Panel –> Internet Options –> Connections –> LAN Settings? You need uncheck this when you are out of office. Outlook caches proxy setting which causes when you are using Outlook from Home, Hotel, etc.,

Outlook may switched to TCP/IP connection mode and trying to connect to the Exchange server using RPC connection. (Pop ups "Outlook is trying to connect…")

To find this issue, Press and Hold Control button on your Keyboard, click on Outlook Icon on Notification area in your task bar, select "Connection Status". The connection column will show HTTPS (for HTTP connection) or TCP.

This is probably the HTTPS URL is not reachable for some reason. So Outlook tried HTTP on first attempt (setting: On slow networks, connect using HTTP first, then connect using TCP/IP), failed over to TCP/IP connection.

Solution: On Outlook Window, Click File –> Work Offline.  Your Outlook goes into Offline mode. Click File –> Work Office again to turn off the Offline mode. See your Outlook connects to the Exchange or not.  Rebooting your laptop works most of the time.

Laptop wakes up from sleep mode at Home or Hotel and Outlook is not connecting to Exchange server (Pop ups "Outlook is trying to connect…" and goes to Disconnected mode)

Solution: If you are sure your Internet connection fine and you can get to Outlook Web Access page using the same HTTPS URL, try closing the Outlook and reopen it.

If closing and opening Outlook doesn’t work, ONLY solution is reboot your laptop. It works most of the time. I believe some RPC connection/session is hung when you were working at Office and it won’t go away till your reboot. (Log off/Log back in does not clear hung RPC sessions)

Outlook goes into Disconnected Mode after being connected (Pop ups for few minutes and goes into Disconnected mode continuously)

This is tricky. Outlook connected via RPC/HTTP and gets some updates (new mails, read mail count, etc.,), then suddenly Outlook pop ups appear (Outlook is trying to connect to Exchange server..). Outlook goes into disconnected mode and tries to connect again. After a while,  Outlook is on Disconnected mode permanently for a while.

Solution: There is a "Back Off" algorithm in Outlook which stops connecting to Exchange server after frequent attempts for 5 minutes. Outlook will start trying connect to Exchange again in 15 minutes.  You can’t wait 15 minutes, Huh! 🙂  Try this,

Outlook: File –> Connect to Exchange

OR

Go to Outlook Offline mode (File –> Work Offline) and switch to Online mode (File –> Work Offline).

Laptop is restored from Backup after corruption, Outlook never connects to Exchange while user can see the mailbox in OWA

Check the following registry keys, set it if it is not looks like below,

[HKEY_LOCAL_MACHINESOFTWAREMicrosoftRpcClientProtocols]
"ncacn_np"="rpcrt4.dll"
"ncacn_ip_tcp"="rpcrt4.dll"
"ncadg_ip_udp"="rpcrt4.dll"
"ncacn_http"="rpcrt4.dll"

While in RPC/HTTP connection, Outlook Address book search fails but works in second or third attempts

For some reason, Outlook doesn’t have a good connection to the Exchange servers.

Solution: Wait for few minutes see the problem goes away (temporary connectivity issues, Exchange server is too busy, etc.,). Try closing your Outlook, wait for minute and reopen the Outlook.

If nothing else works, call your IT guys. Before you start bugging the IT guys, I would recommend to call your co-workers to see their Outlook is working in HTTP mode or not.  😉