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Migrating to Office 365 from Exchange 2010

I need ot migrate our Exchange users to Office 365. I am going to need some help and I have some questions.
1. When I was setting up the trial, it requires me to change some MX records in the external DNS. This I can do, but by doing this will I affect our current users on Exchange 2010? My users cannot handle downtime whatsoever. I want to do this in the most unobtrusive way possible.
2. I am migrating about 400 mailboxes, which method is best used for this?
3. Is there a clear step by step process I can use? I have seen two versions - hybrid and staged and I need to understand what I need for each process.

Thanks

Vasil Michev (MVP)

1) Ignore it. That stupid 'configure domain' wizard is supposed to make things easier for the average Joe, but all it does is to confuse people. Use the TXT record to verify the domain, and do not change any other records unless needed.
2) Cutover migration is very easy to setup and fits the size of your organization. Here's the article: https://technet.microsoft.com/en-us/library/jj874016(v=exchg.150).aspx
3) Use the article above, and also browse the other articles on the left navigation pane, under the "Mailbox Migration to Exchange Online" node. Staged migration is not available for E2010.

The articles for each method are very detailed and should answer most of your questions. There are also video courses available on MVA if you prefer: http://www.microsoftvirtualacademy.com/training-courses/office-guides-exchange-cutover-migration-with-office-365

Salonge

ASKER

Thank so much. I read the articles and even attempted to go through the video course, but this course assumes some things that I don't have. It talks about on-premises which I took to mean my Exchange server. Then it starts referring to a Microsoft Forefront Threat Management Gateway server. Is that something I am going to have to download on my Exchange server?

Vasil Michev (MVP)

Ah no, ignore that part. That's basically the firewall config/making sure the Outlook Anywhere is published externally.

Salonge

ASKER

Okay. That is done. I have Outlook Anywhere already configured with a certificate, so I guess I can skip that part.

Thanks

Salonge

ASKER

One more question. I have everything set up and ready to go, but I only want to migrate a test account to see if it works before I do the entire migration. Also during this migration prior to changing my external DNS, will my user still be able to access their email or will I have to take the Exchange server down to do this?

Vasil Michev (MVP)

Cutover is all or nothing, you cannot migrate single accounts. Only objects hidden from the GAL will be skipped.

The migration process will not impact in any way user's access to the on-prem mailboxes. The only thing you need to worry about is the switch-over, as on a domain joined machines Outlook will default to the local Exchange server for Autodiscover. You can control this by editing the registry keys: http://support.microsoft.com/kb/2212902

Salonge

ASKER

so I can do the migration and it is transparent to the user until i do the switch over in my external DNS? Then once that happens, you are saying that the domain joined machines, which is all, will automatically default to the on-premises Exchange server for Autodiscover?

Vasil Michev (MVP)

Yes. And Yes. In Ex2010, the first thing Outlook will hit in domain environment is the SCP endpoint, which will point all Autodiscover queries to the local server. Use the article above to work around this. Or convert the mailboxes to mail-enabled users.

Salonge

ASKER

How would I convert the mailboxes to mail-enabled users and not affect the current usage or users? There has to be no downtime during this migration.

Salonge

ASKER

Now I am getting the error - We weren't able to connect to the remote server. Please verify that the migration endpoint settings are correct and your certificate is valid and then try again. I ran the Remote Connectivity Analyzer and it passed. In the details it said something about a mismatch name in my certificate, but it has always worked.

Salonge

ASKER

Can anyone help with this error?

Vasil Michev (MVP)

The certificate needs to match the OA FQDN.

Salonge

ASKER

It does.

Vasil Michev (MVP)

Check credentials then, auth method, etc. If using manual config, make sure to specify the correct name of the Exchange server as listed internally, such as 'WIN-NNAQDGPNHR5', etc.

Salonge

ASKER

I think I found the issue. The name of my domain is not on the certificate. The exchange server name is correct though. My certificate has multiple sand.

Salonge

ASKER

Okay. I purchased a new certificate which has my domain name on the certificate. The exchange server name is correct and got the certificate a multiple sans. It also includes Autodiscover.domain name. And I still got the mismatch error and as long as I get this, I can connect in Office 365. What am I not doing?

Validating the certificate name.
     Certificate name validation failed.
      Tell me more about this issue and how to resolve it

      Additional Details

Host name cvhsinc.org doesn't match any name found on the server certificate E=info@plesk.com, CN=plesk, OU=Plesk, O=Parallels, L=Herndon, S=Virginia, C=US.
Elapsed Time: 0 ms.

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Vasil Michev (MVP)

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Salonge

ASKER

Thank you. So how do I do this?

Vasil Michev (MVP)

Talk to the guys that host your site, I'm not that experienced with apache. Here are some example steps: http://community.office365.com/en-us/f/156/t/293985.aspx