Enterprise Office 365 migration can be a scary business! Not only are you dealing with thousands of mailboxes that your end users depend on every single day, but there are so many dependencies, data storage & exporting issues as well as solution design questions to deal with. And while there is plenty advice out there, some of it is inconsistent, out-dated or misleading. So, where do you start?
To give you a starting point, we have compiled a list of the nine biggest Office 365 migration hiccups so you can avoid them:
1) Office 365 Changes. A Lot. Office 365 changes a lot. And I mean a LOT. Last year, Microsoft pushed out more than 450 updates for its cloud business productivity suite last year alone! This can result in a migration nightmare because you need to ensure that you are current in order to be able to implement the best available features in the right way at the time.
2) Scheduling Spider Web. In Outlook, users are often using the delegate function to let other users (e.g., team members, assistants) manage their calendar and mail. This can create spider webs of delegates that are a nightmare to migrate as all the connected mailboxes have to be migrated at the same time. You will have to go into each mailbox, find the delegates (and the delegates of the delegates) and group them together before migration. Also, you have to make sure that the trail does not lead back to the original mailbox you started with.
3) Migrating Public Folders. Migrating legacy public folders to Office 365 can be a nightmare. Since hundreds of users can have access to one public folder, but one user will also have access to several public folders, the migration can easily spiral out of control. Microsoft recommends managing the online public folder mailbox growth using an auto-split feature that splits the public folder mailbox when it exceeds size quotas and then use batch migration to alleviate the problem.
4) Inconsistent Migration Advice. No matter, who you ask, it seems nowadays everyone who has ever had his hand in Office 365 has some piece of (unsolicited) advice to offer when it comes to its migration. There is almost as many opinions and approaches out there as people giving it. Some of it is helpful. But beware - there are also misleading, outdated or inconsistent suggestions out there, that can stall your migration, so make sure, who is giving the advice. Always rely on a reputable source and fact-check.
5) One Size Does Not Fit All. Unless you are starting completely from scratch, you will most likely deal with having to mix on-premise Exchange as well as Office 365. In enterprises, there are many legitimate reasons to implement your mailboxes in a hybrid environment. There will always be certain mailboxes you need tighter control over. Or you need to deal with latency issues connecting to cloud-based mailboxes. It is important to realize that one does not fit all, and the design decisions have to be made with the organization’s goal in mind.
6) Getting derailed during legacy archive export. Archived mail and the file size issues that come with it can become a huge problem for moving to the cloud. There are legacy archive solutions, but they can be very slow and a migration of the legacy data could take several months! Another problem is that most on-premises legacy archive solutions do not work well with Office 365 and you will most likely have to come up with a workaround. You could also use a native export tool to rehydrate the stubbed messages back into the mailbox directly or look to a third-party tool, like Archive 360,, to handle the export, rehydration, and upload process.
7) Retention Limits & Litigation Hold. Regular Outlook message retrieval is one of the biggest pain points for admins, but with a default retention limit of 14 days for Office 365, this will quickly become unbearable. Even if you extend this limit, you will max out at 30 days. For all mailboxes that need to save their messages longer, Microsoft recommends placing these on litigation hold.
8) Go Big Bang Or Go Home? Another key consideration you have to make is to figure out your migration approach. You can either do a full-blown big bang migration or a partial migration where some items move to Office 365 while others stay, or slowly using tools that sync your data between the source environment and the target to maintain access across the disparate infrastructures. Understanding the impact of each choice is a key hurdle as it will result in either more risk or more cleanup!
9) Choice Of Migration Tools. Finally, it is important to think about which tools you will be using for your migration. The tools that Microsoft provides are quite basic, but certainly adequate for small businesses. Medium-size businesses to enterprises are looking at more sophisticated tools such as Dell Migration Manager, Binary Tree, SkyKick, who will execute the migration for you. Setting up these tools is complex and requires a project management team that truly understanding the entire end-to-end process. The hurdle here is to decide whether or not to use these tools at all, and if so, which and how put the correct team in to implement them successfully.