Tips and Tricks for your Office 365 Migration

Having a Hybrid Exchange environment lets you move to the cloud on your terms.   You can co-exist with users on premise and in Office 365 for as long as you want and the user experience is virtually identical.   For your administrators, they do not have to re-learn a whole new set of tools and commands to manage users and can work with familiar Exchange 2010 snap-ins and PowerShell cmdlets.

Which brings us to the topic of today’s post.   If you have setup a hybrid organization, it’s likely because you have a well-established exchange organization and are using many of the features that are offered to you in Exchange 2010.   You’ve probably taken advantage of Unified Messaging, retention tags and policies or have allowed users to get away with storing large emails in their mailbox.   When moving to 365,  your users are going to expect things to work just like they did on premise and you’re going to want to make sure you can do it without performing a complicated run of tasks after every move.   Today we’ll go over a few steps you can follow to make sure your on boarding process to 365 is as seamless as possible.

Maintaining UM Mailbox Settings

If you are using Exchange UM for Lync or as a voicemail solution for your PBX you’ll need to make sure that you re-create your on-premise UM Policies in Office 365 to continue to provide voicemail services.   By default, you cannot move a mailbox that is UM enabled to Office 365 so you would have to first remove the UM feature from a user, start their mailbox move and then finish it when you are done.   This could potentially lead to a bad experience for a user if someone tried to leave them a voicemail while their mailbox was moving.   

Fortunately, there is a way to make the process seamless to the end user.   Hidden within the set-ummailboxpolicy cmdlet,  there is a flag called SourceForestPolicyNames,  what this will let you do is create a mapping between your On-Premise UM mailbox policy and your cloud policy.  For example: 

and then on premise

Using these you can now perform a mailbox move without turning off voicemail first.

IMPORTANT:   If you are not using Lync as your PBX, be sure to have the move request suspend before finishing the move. Otherwise the voicemail for a user will stop working until you have a chance to go back and update your PBX to point to the new voicemail location.

Skipping Large Items

Another area where administrators often run into problems is dealing with large items in user mailboxes.   Office 365 has a limit of 25MB on their transport servers and a soft limit of 35MB on data in the mailbox itself.  This gives you a little bit of leeway on moving items as if someone has an item near the limit it will still get into 365.  However you still can have users that may have sent messages larger than that in their on premise environment for whatever reason.   We’ve previously blogged about ways to find large items in mailboxes however making sure your users delete them all is another story.   Fortunately Office 365 provides a way to be able to move your mailboxes without worrying about a move failing due to large items.   That setting is largeitemlimit.

Similar to -baditemlimit, largeitemlimit can be configured to override the threshold for the number of items that will be skipped during a move without stopping the move outright.   This variable is only available via PowerShell so your going to have to kick off your moves with the new-moverequest cmdlet.   Using it would look something like this:

This will run a remote move request that will skip up to 40 corrupt items and 40 large items in the mailbox and then put it on hold right before you are done so you can fully control the migration experience.

Hopefully these quick tips will help you out as you are planning to move your email services out of your datacenter and to the cloud.