I m in the migration process of exchange 2010 (SP3 RU5) to exchange 2013 (sp1). 

Just completed installation of MBX2013 and CAS2013 servers on same subnet and configured virtual directories, i started to get client complains of sending and receiving mails on Outlook (2010 sp1/ 2013). Sometime mail stuck in outbox or not receiving mail until restarting outlook. 

Still not done the DNS redirection to 2013. 

Mostly close and reopening the outlook was solved the issue. But time to time issue occurring. 

Then i have moved the all outlook users "outlook anywhere" with NTLM. But still i m getting queries from users time to time. 

I have checked 2010 "CAS Array" settings and could found the MBX2013 server has automatically added to cas array as a member. 

I dont see any client connections to CAS2013 or MBX2013 yet. 

Is this adding 2013 to "cas array" is normal?

What could be the reason for mail issue of Outlook users? How can i troubleshoot?

Hi ,

Q1. Is this adding 2013 to "cas array" is normal?

Know to my knowledge none of the queries will get forwarded to the exchange 2013 server unless the DNS record's are pointed .

By default when you add the exchange 2013 client access server in existing exchange 2010 environment results in adding the new exchange 2013 to existing the CAS array and that change will not harm anything in the existing environment.

As an additional info there is no use of CAS array in exchange 2013.

Q2 : What could be the reason for mail issue of Outlook users? How can i troubleshoot?

We need answers for the below questions to start troubleshoot.

Is this issue is affecting all the users ?

If so does all the users belongs to same database ?

Are they connecting exchange 2010 from LAN or from internet through outlook anywhere ?

Apart form this change what is the last change that you have done in your exchange 2010 servers ?

Moreover we need check the exchange core services status on the mailbox server by using the below mentioned command ?

test-servicehealth | ft -au

What happens when the affected user tried to send the email via OWA ?

Have you checked the error and critical events on the application logs in the mailbox server ?

Hi Dilan,

According to your description, I noticed that the issue could be solved temporarily when closing and reopening the outlook.

Please confirm whether the problematic user can send and receive messages in OWA. In Outlook, please click Send/Receive tab to Send/Receive all Folders and show the process to confirm if there is any error.

Additionally, please re-configure the account with a new Outlook profile to have a try.

https://support.microsoft.com/en-us/kb/829918

Re

Dear Nithyanandham / Winnie,

Thanks for your attention. 

Find the bellow answers for your quires,

Is this issue is affecting all the users ?

Yes. intermittently. not all users facing the issue simultaneously. But few times restarting outlook solved the issue and then users remain clam for rest of the day. But again other morning issue arises. If i would say around 10% of total users facing the issue. 

does all the users belongs to same database ?
No. users in diffrent DB's and using offline address book of 2010 

connecting exchange 2010 from LAN or from internet through outlook anywhere ?
LNA and Internet. both are facing the issue time to time. 

what is the last change that you have done in your exchange 2010 servers ?
As explained, have moved the all outlook users "outlook anywhere" with NTLM. But this has done as a solution for slowness. It gains some improvement but issues are there from users time to time. 

when the affected user tried to send the email via OWA ?
OWA was fine and we were asking users to use OWA until outlook get stable. 

error and critical events on the application logs in the mailbox server ?
Unfortunatly in mailbox servers i could found logs for 2 hours. nothing can considered from that. CAS servers having some erros but not relevent this issue. Anyway I ll increass log capacity and try to get more logs in Mailbox. 

test-servicehealth | ft -au

RunspaceId                           Role                RequiredServicesRunning ServicesNotRunning ServicesRunning   
----------                           ----                ----------------------- ------------------ ---------------   
7f32bd9c-d344-43a9-87af-044a0718110b Mailbox Server Role                    True {}                 {IISAdmin, MSExchan
                                                                                                    geADTopology, MSExc
                                                                                                    hangeIS, MSExchange
                                                                                                    MailboxAssistants,
                                                                                                    MSExchangeMailSubmi
                                                                                                    ssion, MSExchangeRe
                                                                                                    pl, MSExchangeRPC,
                                                                                                    MSExchangeSA, MSExc
                                                                                                    hangeSearch, MSExch
                                                                                                    angeServiceHost, MS
                                                                                                    ExchangeThrottling,
                                                                                                     MSExchangeTranspor
                                                                                                    tLogSearch, W3Svc,
                                                                                                    WinRM}            

What do you mean by "the MBX2013 server has automatically added to cas array as a member"?

Dear Li Zhen,

MBX2013 (Mail Box server 2013) has automatically added to 2010 CAS array soon after completion of installation. 

I mean how do you determins that?