Office 365 Migration - Currently have EOP

[office 365admin]

Hi Guys,

I was wondering if someone could assist.

We currently have Exchange Online Protection which is set up in the office 365 portal. We have all our users already synced to this office 365 tenant aswell as our domains.

We are looking at moving our office and mail from on premise to office 365.

My question is, as we already have a tenant setup with the users synced, do I need to create a new tenant in order to start setting up office 365, or can we utilise our current one? 

Also, if we use our current tenant, do I need to remove and re-sync our users with AD Connect? 

And finally, at what point does the users online mailbox get created, is it when the users syncs from our local AD to the tenant, or is it when you purchase the licence and turn on mail for the user?

Many Thanks,

Alex

[#2]

No and No, no need for a new tenant or resync. You need to actually migrate the mailboxes though - the sync process does not cover that part. Depending on your on-premises environment, there might be several methods available as detailed here: https://support.office.com/en-us/article/Decide-on-a-migration-path-0d4f2396-9cef-43b8-9bd6-306d01df...

Usually, Hybrid is the preferred option as it offers the best experience.

[#3]

Thank you for the response and link, its very helpful.

We are currently running terminal servers at the moment and will hopefully be moving to Citrix next year after the Office 365 deployment.

My question is, in a non-persistent environment, is it better to go with the Hybrid deployment?

Thanks again,

Alex

[#4 · Accepted solution]

Can you clarify what you mean by a non-persistent environment? For example, do your users connect to Exchange today using OWA only, or Outlook in 'online mode?'
The reason I ask is because Exchange Online works best when users connect either via OWA, or Outlook in 'cached mode.'
This presents a problem if your RDS/Terminal Server/Citrix environment is setup for Outlook in Online mode because usually it results in sluggish performance, slowness when switching between views (between calendars, especially if using delegation) and large mailboxes. One work-around is to use Outlook in Cached Mode but using a GPO to redirect the OST files to an external NAS/SAN so that the local RDS server doesn't have its HD fill up from all the OST files. Another option is if users previously used Outlook in Online Mode, convert them to start using OWA.
Or when you say non-persistent, do you mean more like VDI where the desktop gets refreshed/cleaned/wiped when the user logs off (or is that what you will soon be moving to)?
Regardless of the issues above, your question on whether to go Hybrid or not has nothing to do with persistent desktops or non-persistent desktops... Think about Hybrid as the right way to migrate Exchange on-premises to Exchange Online because it provides the best user experience during the transition phase. Just a few of the benefits are:
- Slowing migrate pilot groups to test functionality like free/busy and mail flow
- Unified Global Address List between cloud and on-prem (important if you are going to slowly migrate over days/weeks)
- SMTP domain name co-existence between on-prem and cloud, allows you to slowly migrate users while they get to keep their primary SMTP name the same
- Preserves the OST file, since the Mailbox GUID remains the same, there is no rebuild in the OST after the mailbox migrates to Exchange Online (preserves lots of internet bandwidth)
- Provides a friendly redirect to Mobile phones to automatically migrate their profile (in most cases)
- Provides a friendly redirect to OWA if the user tries to logon to the old OWA page
- There are other benefits to going hybrid but I recommend you engage a Partner or Microsoft Fasttrack to assist you (Microsoft FastTrack can give you some lightweight design assistance if you have more than 50 licenses, but they won't actually migrate the mailboxes for you unless you have more than 500 licenses, see their article here: https://technet.microsoft.com/en-us/library/office-365-onboarding-benefit.aspx)

[#5]

Thank you for the reply, you have cleared up all the grey areas I had.

I will continue with the hybrid deployment now in our current environment, then and once we go to Citrix Xenapp, I will setup the GPO to point the OST file to a different network share, we will then put Outlook in Cached Mode and hopefully that should be good performance wise.

Thanks again!

Alex 

[#6]

Hi, 

I think the problem in this scenario is that as soon as the mailboxes are migrated to Office365(cutover) the mail will start to be delivered to Exchange Online instead of onprem and as you need time to configure new Outlook profiles you do not need this behavior. Unfortunately, Microsoft documentation is very slim when it comes to onprem + EOP to Exchange Online migration. In this scenario i think you need to set your MX records back to onprem, do the cutover and then point back your MX to Exchange Online. You will, however, lose the EOP during the cutover. 

Correct me if I am wrong!

[#7]

correction: I wanted to say "as soon as mailboxes are synced with Office365"

Your MX already point to Office365 due to EOP =>as soon as the mailboxes are synced from onprem 

Office365 will start picking up the emails.  You do not want this as new outlook profiles are needed.

[#8]

No, we are not recommending a cutover. We recommend Hybrid to avoid those problems. A properly done Hybrid will allow Autodiscover to automatically update the Outlook profiles, Mobile Profiles, and a friendly OWA redirect too.

Thanks,
Joe

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@Alexandru Dragomir wrote:

correction: I wanted to say "as soon as mailboxes are synced with Office365"

Your MX already point to Office365 due to EOP =>as soon as the mailboxes are synced from onprem 

Office365 will start picking up the emails.  You do not want this as new outlook profiles are needed.

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[#9]

Hi
In my situation the onprem is Exhange 2007. In order to install 2010+ you need time, hardware resources and the risk. Its unbelivable that MS did not think of 2007 + EOP to Office365 via cutover

thanks

[#10]

Two things..
1) You should post a new thread to discuss your Exchange 2007 issues, this particular thread is about suggesting solutions for an Exchange 2010 scenario. It is not helpful to discuss your cutover for Exchange 2007 as a solution to someone running 2010, at least not in my opinion.
2) I disagree with you that 'its unbelievable for MS to not think of 2007' ... Here is why.
Microsoft's policy is to support the past two versions (N-2), so consider yourself lucky that Exchange 2010 works in Hybrid at all with Exchange Online because it is an N-3 product, since Exchange 2016 and 2013 are also available. It's not reasonable, in my opinion, to expect a software developer to support an N-4 support model. If you disagree, you have not been a programmer trying to write code from what was probably four separate teams of programmers. The reality is that your organization is experiencing "technology debt" as they have avoided upgrading Exchange for far too long and now they are paying the price for that debt. That debt means you can't avoid an upgrade to 2010 to properly provide the best user migration experience to Office 365.. your users deserve a better experience than a cutover experience due to this technology debt of not upgrading for this long.