Office 365 Pre-Migration & Post-Migration Checklist [2019]

Title Image for The ultimate Office 365 Pre-Migration & Post-Migration Checklist

A comprehensive Office 365 Migration Guide that explains on key things to consider when migrating to Office 365 & help in preparing your o365 Migration Plan. Also, includes some useful tips & best practices while carrying out o365 migration.

Organisations come in all shapes and sizes so the complexity of your pre and post migration checks will depend where you sit on size scale. If you are migrating to Office 365 and you have a couple of PC’s and mobile devices, then spending weeks planning a complex migration would be crazy and unnecessary when you could literally write down your plan on a sheet or two of scrap paper.

If you have two users and something goes wrong, then it’s not the end of the world and you can recover pretty quickly from most situations. From here however the complexity increases as the organisation grows. More devices, more software, more configuration, more locations and more people. The larger the organisation the more critical the planning and the more people and organisations affected if you get it wrong.

In this blog we go through an outline of what you need to be considering when carrying out your pre and post migration.

Office 365 Pre-Migration & Post-Migration Checklist
Office 365 Pre-Migration & Post-Migration Checklist
o365 Pre Migration Checklist

  • Plan your project – Communication is key
  • Inventory your current environment
  • Review your current environment
  • Prepare for your migration
  • Set up Office 365

o365 Post Migration Checklist

  • Email device redirection
  • Email caching to local device
  • Email signatures
  • Personal rules
  • Email plugins
  • Sharing your mailbox calendar and folders
  • Local PST archives
  • Skype for business
  • Auto Complete
  • SharePoint content
  • Permissions

Let’s dive right in.

You can migrate a maximum of 2,000 mailboxes from your on-premises Exchange organization to Office 365 using a cutover migration. The recommended number of mailboxes, however, is 150. Click To Tweet

As organisations differ greatly our proposed checklist won’t cover all eventualities but what we hope it does give you a starting point with areas you need to consider and then from there you can include, dismiss or add additional checklist items you feel you require for your organisation.

Plan your project – Communication is key

  • It goes without saying that everyone involved or affected by your migration to Office 365 needs to understand what you are trying to achieve.
  • Everyone needs to know why you are moving to Office 365, what you are moving and when and how long it will take you to get there.
  • A migration to Office 365 (o365) will bring significant change within your organisation so what will be the impact and who will it affect. Does everyone know this and is everyone on board with your plans.
  • Decide on how you plan to run your projects and how information will be disseminated to all involved.  If you have decided on a time frame and on the day you start migrating, your sales team launch a major email campaign then it’s not going to please your sales exec.

Inventory your current environment

  • Collect the names and email addresses of the users.
  • Collect the number and size of mailboxes (including shared resources).
  • Collect client versions and configurations (browsers, operating systems, office applications, mobile versions).
  • Collect information on file storage locations (file shares, intranet file storage).
  • Collect details on your network settings (DNS hosts, proxy and/or firewall configuration, internal switches, internet connectivity and available bandwidth).
  • Review your configured DNS records.
  • Collect details about any intranet sites that you plan to migrate.
  • Collect online meeting and Instant Messaging systems that you plan to migrate.
  • Collect the details about any applications that are integrated with existing systems (mail enabled applications, workflow, CRM, and so on).
  • Where does you current CCTV system save its images or your door entry system keep its entry logs. This server may be disappearing soon.

Review your current environment

  • How will you create and/or synchronize accounts?
  • Do you plan to link your existing systems with Office 365 or will your new cloud system be standalone? Depending on the answer you could do the following: – – You can add users manually. – Use a spreadsheet and add many users in one go. – Use the Windows PowerShell tool to create user accounts. – Use Azure AD connect to replicate the users from Active Directory within your exiting environment. Not forgetting to add the Office 365 license to the created account. – Take a look at this article for more details
  • How will user accounts be authenticated?
  • What licenses will you need. Will they be covered by Office 365 or will you still need local licenses?
  • How will your devices antivirus be managed? If it was managed and run from an internal server, will that server remain or will you switch to a cloud based solution?
  • Review backup policies, do you need to backup office 365 or organization safety and /or compliance?
  • Will you migrate any data and how will that migration occur?
  • What tools do you plan to use to complete you migration, for example our email Migration Solution Migration Monster
  • What devices will users be able to connect from (remotely, from mobile devices, or just from your network)?
  • Will your devices work fully with Office 365. Will they need replacing or upgrading?
  • How will your network cope with the new method of use? Do you need more bandwidth or more resilience? Also, is your internal network capable of coping well with the new use? Data that once mainly went between your file servers and desktops may now be heading towards your internet connection and out of your network. How many users will be using Office 365 , what will they be doing? Calculate how much bandwidth you think you will need and the add at least 20% to cover peak loads.
  • Look at the layout of your internal network which may also be optimized for mainly internal traffic. Will your switches, firewalls and routers need upgrading?
  • Are your users familiar with office 365, will they need training?
  • Decide if you need to change any of your goals or timelines based on your planning so far  

Prepare for your migration

a) Get Active Directory ready (if connecting it to Office 365)

  • Make sure information within active directory is correct/up to date and that unused accounts are removed if no longer required.
  • Ensure that each user has a valid and unique email address in the proxyAddresses attribute.
  • Check for a valid and unique value for the userPrincipalName attribute in the user’s user object. On premise UPN will need to match the Office 365 UPN.
  • Make sure information held within the Global address list is correct.
  • Run the Office 365 IdFix tool to search for problems in your directory.

b) Get your data ready.

  • What data and emails do you need to move to Office 365 or can it be archived online or offline?
  • Do you need to migrate years and years of emails? The more you migrate, the longer it will take.
  • Can you archive emails or data that you no longer need?
  • Do you need to meet compliance requirements in terms of what data (including emails) you store and how long you retain it for? Again, reducing the amount of data will speed up your migration but it may also reduce your storage costs on Office 365.

c) Get your network ready

  • Increase internet bandwidth were required.
  • Put internet redundancy in place if required or can users work elsewhere if the internet goes down.
  • Upgrade switches routers and firewalls if required.
  • Re configure/replace your antivirus management solution.
  • Remove out dated DNS records that are no longer used, DNS records can get very messy over years. Reduce TTL times on records you know you will be changing to 3600 seconds
  • Make sure your DHCP ip pool will be large enough to cope with all your remote workers visiting site with their devices to be re-configured .
  • Update client software
  • Will the operating system you have support Office 365?
  • Will the web browser you are using support Office 365?
  • Will the version of .Net support Office 365
  • Upgrade/change to your antivirus software as required
  • Replace slow or unsupported devices
  • Will your PC’s, Laptops and mobile devices cope with the new style of working
  • Prepare your organization and users
  • These videos are a helpful tool
  • Checkout the office 365 training center
  • Make sure that all you staff know how they should log in and where their data will be on the new system. Inform them of any new processes they should follow on the new system if the old processes have changed. Make sure they are aware of how the changes will affect them.
  • Prepare your support staff and migration team for what will be expected from them, what will be happening and in what order.
  • Active Directory Rights Management If you have Active Directory Rights Management Services. Prepare your environment.

Set up Office 365

  • Configure your Office 365 subscription including licensing .
  • Add your domains to office 365.  Each domain will need to be verified before its added to Office 365. There are multiple methods of doing this and it will depend on which DNS provider your records are hosted with. Office 365 will prompt you on what to do and which records will need to be changed.
  • Configure all the applications you plan to use. E.g Email, messaging, web collaboration and SharePoint.
  • Configure security on Office 365. You may wish to replicate security permissions on files and other items to match the configuration on your old system or start a fresh with a new structure.
  • Check out this article for a more detailed look at Office 365 security and options available to configure using Secure Score  . Review Secure Score before and after your migration.
  • Prepare your office 365 directory synchronisation if required
  • Configure single sign in if required.
  • Configure email footer rules for outgoing emails
  • Review your security and compliance requirements on Office 365. If UK/ Europe based, then GDPR compliance requirements will need to be met.
  • Carry out test data migration using your selected tools.
  • Carry out test email migration using your selected tools
  • Test user access to Office 365.
  • Carry out your Migration and redirect your domain records (MX and Autodiscover) 

The amount of time it takes to migrate mailboxes to Office 365 is determined by the available and maximum capacity of your network. Click To Tweet


So the migration has been carried out and all your data should be sitting where you expect it on the new system. If you’re a two user organisation a quick glance at your data areas will give you a good idea how things went and if you still have your correct data. If you own the data you will easily recognise it and if it’s all there, you will relax and get back to work on your new Office 365 system.

However, the larger the organisation the more likely you are to have never seen the data you are migrating before so this requires the owners of the data to check for its availability.  

Speak to each individual or department that owns the data and get them to check that everything is there as turning back after this point may prove to be very difficult.

Here is a list of thing that will need to be addressed after your move for your Office 365 post migration checklist:-

a) Email device redirection

  • All devices that require access to your email accounts will need to be redirected to Office 365. For many devices this may just mean an account deletion and recreation for the device to pick up the new location, MS outlook however can be a little more complex.

b) Email caching to local device

  • Double check the o365 migration has completed populating folders to your local Outlook profile. Open up each folder — it should say “All Folders Up To Date” or “This Folder Is Up To Date”.

c) Email signatures

  • Your email signatures will need to be re-entered back in to your mailbox.

d) Personal rules

  • It’s unlikely that your migration will have included personal rules so your users will need to recreate them and will need to be informed about this. We suggest using the webmail client to do this.

e) Email plugins

  • Email plugins may need re-installing on your outlook client

f) Sharing your mailbox calendar and folders

  • If your folders or calendar where shared out before the migration this will need to be re-established on the new system

g) Local PST archives

  • You may wish to import your local PST files in to Office 365 and then use Online Archiving to keep them more securely. Consider importing them.

h) Skype for business

  • If you plan to use Skype for business you may need to add your contacts.

i) Auto Complete

  • When you start typing the name of the person you would like to email, auto complete will then make suggestion. This function can be copied across from the mailbox by making some local device changes.

j) SharePoint content

  • If you had SharePoint before the move to Office 365, make sure all your content has replicated across correctly and is visible again.

k) Permissions/security

That’s it, you can now sit back with a successful migration completed and if all considerations covered then a quiet time from your end users as well. We hope this migration checklist helps you build your Office 365 migration plan.

Please comment on this article below if there is anything you would like to see added or amended.

Happy migrating.

Migration Monster Team

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