Outlook 2010 very slow on initial connection to Exchange 2010

When you launch Outlook or setup for the first time it takes 2 to 3 minutes for Outlook to connect to exchange 2010.  This is all LAN traffic, fully patched Office and Exchange SP3.  Why does it take Outlook so long to connect?
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Will SzymkowskiSenior Solution ArchitectCommented:
The first time you launch Outlook it has to create the profile and download the mail from the server (cached mode) to the client machine. Depending on how big the mailbox is it could take awhile before all of the mail is downloaded to the client.

As for the actual time it takes to load and start using Outlook it should not take that long. You might want to make sure that your DNS and Autodsicover URI has been configured properly.

AmitIT ArchitectCommented:
Do you have any HLB? How many servers you have in total and what happens after outlook is connected? Is it still slow?
PUAlumniAuthor Commented:
Amit, once Outlook is open no issues.  Sorry, I'm not familiar with HLB.
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PUAlumniAuthor Commented:
Will, this is a small office and VERY small mailboxes.  Thanks for the URI tip, I forgot about that one.
AmitIT ArchitectCommented:
HLB is hardware load balancer.

Can you ping server from client machine and check the result. Also, run tracert to find out, if server is reachable properly or not.

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Will SzymkowskiSenior Solution ArchitectCommented:
@Amit - the client does connect eventually so i doubt it would be a connectivity issue however if DNS is not properly setup or Autodiscover is incorrect this could be the reason why it is taking longer than expected.

It could also be the client machine as well if this is the only machine being affected.

PUAlumniAuthor Commented:
Amit, no HLB.  Tracert one hop (netBIOS name) replies with IPv4 address <1ms.  

Will just checked DNS and all looks right and URI also correct.  All URL's point for FQDN and I have a custom DNS zone that points to the mailserver's private IP address.  OWA loads fast, Outlook very slow.
PUAlumniAuthor Commented:
@Will, all clients take a long time to connect.  Once connected no issue.
PUAlumniAuthor Commented:
FYI, this is a domain that was upgraded from SBS2008 to two 2008R2 DC's, a Fileserver, and a Mail Server.  SBS2008 gracefully demoted and removed some time ago.
Simon Butler (Sembee)ConsultantCommented:
First thing I would be looking at is whether it is connecting via TCP or HTTPS. This sounds like timeout issues with failover.

Hold down ctrl and right click on the Outlook icon. Choose Connection Status. Check the protocol.
Another option would be to close Outlook then choose run and type

outlook.exe /rpcdiag

That brings up the same screen, but crucially right from the start, so you can see the connection attempts.
On the same right click with ctrl menu, there is an Autodiscover test. I would run that to see if something is timing out.

PUAlumniAuthor Commented:
Simon, thanks for tips
Started with Outlook /rpcdiag no errors, just took a long time to connect, tested autodiscover, no issues I could spot, Connection status shows HTTPS
Simon Butler (Sembee)ConsultantCommented:
The long time to connect is obviously where the failover is happening.
For whatever reason the client is unable to connect to Exchange using RPC over TCP and therefore is failing over to RPC over HTTPS.

That is a networking issue, something blocking the traffic, name resolution failure, something like that.

PUAlumniAuthor Commented:
Final solution came from MS support.  netsh advfirewall firewall add rule name="Open Port 135" dir=in action=allow protocol=TCP localport=135

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