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Migrating to Microsoft 365

At some point in time, businesses may consider transferring from one email server to another for better and/or additional operations, or maintain the two. In this article, we are giving you a bird’s eye view of the transition from your on-premises emails to cloud emails. Whether you are a small or big business, you may consider the following to migrate from your on-premises email and Hosted Exchange Email to Microsoft 365, formerly known as Office 365.

1. On-Premises Email vs. Cloud Email: 

Companies may maintain their own mailboxes which come with calendars and contacts, similar to having in-house emails; these types of mailboxes are called on-premises email. Businesses may also use free webmail solutions, such as Gmail and Yahoo. Then, they may employ one IT specialist who should take care of updates and maintenance of these email servers.

On the other hand, Microsoft has developed HostedExchange as an email solution to help firms maintain email servers in their own datacenters. With Hosted Exchange Email, businesses look like they are renting some space at Microsoft for their email servers. By using Hosted Exchange, businesses need not much technical knowledge on managing email servers as Microsoft takes the responsibility of maintaining and updating everything. With Exchange, businesses are able to access tasks, calendars, and contacts from phone, tablet, and laptop.

However, another type, Microsoft 365, offers cloud-based services, so similarly it frees businesses from managing mailboxes on-site, giving Microsoft the responsibility for updates and maintenance. The difference Microsoft 365 has from the latter is that Microsoft 365 adds more productivity because account users are able to access files, contacts, and emails not only through any device but also anytime, anywhere there is Internet connectivity. If it is about upgrades and maintenance, Microsoft 365 does both without users even noticing it.

With these three email servers generally discussed, your business may decide whether it needs migration from one to another. The decision usually lies on a lot of factors, such as pricing, accessibility, and even scalability. Thus, you should think carefully if there is a need for such transfer.

2. Initial Questions to Ask Yourselves: If you have made up your mind and would like to migrate to the cloud email solution brought by Microsoft 365, here are some questions you have to ask yourselves:

a) What email server have you been using?: Whether you are using your on-premises email solution or let a third part be responsible for your email servers, migrating to Office 365 requires certain requirements from the type of email server you are using; one is your business should be using – but not limited to – Microsoft Exchange. Please read through the following sections to learn more about this.

b) How many mailboxes are there in your business that we are supposed to migrate to
: As a general idea, it is a need for your IT specialist to know how many mailboxes are up for migration. With this number at hand, your solution provider – could be us Fisch Solutions – is able to identify the appropriate method of migration to follow.

c) How much time does migration need?: Bad news is maybe you do not have the choice as to how long the migration should take. Good news is with the right method of migration, we may be able to estimate how long. We know businesses need to use their mailboxes, calendars, and contacts among others immediately, but for a successful migration, time is of the essence.

d) What Microsoft 365 plan are you taking?: Microsoft 365 or Office 365 offers plans for home, business, enterprise, and education. Thus, as the names suggest, you should know which purpose you have for buying a Microsoft 365 plan. For your business, the price ranges from USD$2.5/user/month to USD$20/user/month for Microsoft 365 Business Basic and Microsoft 365 Business Standard, respectively. However, this time, prices may not take priority; note that since each plan comes with a description, you should read them carefully and assess which is best for your business needs.

Let’s say you have answered the questions above. So now you are ready to take on something technical – possibly more technical. Remember that the ones specified for you are among other questions you may encounter when you process the migration.

3. Method of Migration to Office 365: When you have decided to migrate your mailboxes to Microsoft 365, you should choose the method of migration that you think is appropriate for your business.

a) Cutover Migration: Microsoft talks about cutover migration in detail. In the following table, we have outlined general information about cutover migration method.
Parameter Cutover Migration
Meaning You may follow cutover migration if you want to move the contents of your mailboxes to O365 all at once.
When Suggested – if you have been using Microsoft Exchange Server 2003 or later – if your Exchange has fewer than 2000 mailboxes
How Long Migration Takes – If you plan to move all the mailboxes of your entire company to O365, you can move them at one time. However, the migration may take a day…or a few days. Assuming you followed the steps correctly, migration might take a little faster. Still, a lot more factors should be considered. – While cutover can accommodate a maximum of 2000 mailboxes, Microsoft recommends cutover for 150 or fewer. Small businesses with less than 150 mailboxes to move can definitely take advantage of this method.
Impact to Users (Post Setup) – Potential Delay in Emails: When someone sends an email to your on-premises mailboxes (that have already been migrated), there is a chance the email goes to the on-premises email, not the O365 (at least initially). Therefore, for cutover migration, your tech should make changes in something called MX record. Your MX record identifies where emails are sent. After cutover, ask the tech to adjust the MX record and set it to O365. This way, your migrated mailboxes receive the email you are expecting.

b)Staged Migration (or Waved Migration): If you plan to migrate through staged migration, it is worth reading through its details.

Parameter Staged Migration
Meaning If you are thinking of migrating your mailboxes to Microsoft 365 over time, not all at once, you may consider staged migration.
When Suggested – Note that MS Exchange 2003 and 2007 have ended support in 2014 and 2017, respectively. Thus, if you have been using these email servers, moving your mailboxes to Microsoft 365 through staged migration may be for you. – Staged migration can settle only mailboxes. On the other hand, contacts can be transferred through another procedure called directory synchronization.
How Long Migration Takes – Staged migration can take care of transferring more than 2000 mailboxes of yours to Microsoft 365. – Considering that you may be transferring 2000 mailboxes or more, migration can be set up in two stages, so your company may decide which mailboxes should be migrated first and second. Further, business may (and some not) take a break on weekends, so staged migration can be done over the weekends when employees do not need to use their emails.
Impact to Users (Post Setup) – Once staged migration is complete, users have to create their new Microsoft 365 profile through Outlook, and Outlook is the one that connects them to Microsoft 365. This process is a little different from cutover migration; in cutover migration, users who have migrated on-premises mailboxes are new users in Microsoft 365.
c) Hybrid Migration: Hybrid migration allows on-premises mailboxes to work jointly with Microsoft 365.
Parameter Hybrid Migration
Meaning If your business has more than 2000 mailboxes to migrate, hybrid migration is another option. However, its difference from staged migration is that, businesses who migrate to Microsoft 365 would prefer to maintain both on-premises and Microsoft 365 mailboxes.
When Suggested – When hybrid migration is followed, businesses would like to see mailboxes, calendars, tasks, and contacts in on-premises and Microsoft 365 environments. Other companies take on hybrid migration because they would like to keep a group of mailboxes in their on-premises environment and another group on Microsoft 365. – If you are planning to move your mailboxes to Microsoft 365 through hybrid deployment, take note of the following pre-requisite versions of Exchange: Exchange 2019, Exchange 2016, Exchange 2013, and Exchange 2010.
Impact to Users (Post Setup) – With hybrid migration, businesses are sure to have replica of information in both on-premises and Microsoft settings. While hybrid migration handles consolidated environments, data from on-premises and M365 may intermittently work unsynchronized, hence lessening productivity and collaboration.

 d) IMAP Migration: If your business does not use Microsoft Exchange, you may move your mailboxes to Microsoft 365 through IMAP migration.  


Parameter  IMAP Migration 
Meaning  Migration methods such as cutover, staged, and hybrid require that on-premises mailboxes be from Microsoft Exchange versions. However, if businesses do not use on-premises Exchange, they may turn to IMAP migration.  
When Suggested  – Only IMAP-enabled mail servers, such as Gmail, Yahoo Mail, AOL, Verizon, and AT&T, can be migrated to Microsoft 365 through IMAP migration.  
– If IMAP migration is followed, businesses should take note that only 50,000 mailboxes can be moved.  – Additionally, through this method, only mailboxes can be moved; contacts, calendars, and tasks are never migrated. 
Impact to Users (Post Setup)  – This may be a hassle, but IMAP migration requires the creation of users in Microsoft 265 before moving mailboxes from the on-premises server.  

Based on the needs of your business, moving data may take a minimum of 8 days and maximum of 45 days for a mailbox size of a maximum of 200gb; however, if the size covers around 1 to 10 gb, 1 day or 1 week may be enough.  


Mailbox Size (gb)  50th Percentile Duration (Days)  90th Percentile Duration (Days) 
1 – 10 
10 – 50  14 
50 – 100   30 
100 – 200   45 
>200  Not Supported  Not Supported 


On the other hand, Microsoft specifies that if you have 1 million mailboxes to migrate, moving data may take at least 60 days and may reach up to 180 days; nevertheless, if you have less than 1000 mailboxes for migration, give the process a min of 5 days and max of 14 days. Microsoft provides the following table that shows migration duration to complete 90% of mailbox moves:
Number of Mailboxes Duration (Days) May Take Up To This Many Days
<1,000 5 14
1,000 – 5,000 10 30
5,000 – 10,000 20 45
10,000 – 50,000 30 60
50,000 – 100,000 45 90
>100,000 60 180

In a nutshell, with all these above mentioned details, your business has a choice as to which migration method is appropriate. Also, the number of employees your business has is not the only factor to take into account. No matter how much you want migration to complete, you need to allow the process to proceed as efficiently as it should. Therefore, we know you want it fast, but remember that even migration needs time.

Factors that Affect Migration to Microsoft 365: The following are some of the factors that may make migration either a little quicker or slower:

a) Data Type and Density: This factor is an obvious case because as a general rule 1gb mailbox may be faster than a 10gb mailbox. However, you should consider the number of mail items a mailbox has. For example, a 1gb mailbox with 100 items may migrate faster than a 1gb mailbox with 10,000 items.

b) Network Capacity: If you are able to determine how much you are to migrate in gb, then you should also evaluate your network capacity, by asking your Internet service provider for allocated bandwidth and restrictions. Knowing the capacity of your network may affect how much time you need for the migration. Also, gauging your network may help detect potential network stability and delays.

c) Back End Tasks: It would be great and/or ideal to let migration be the only process your computers have while you are moving data; however, computers do not work that way. At least, when migrating to Microsoft 365, no other CPU intensive tasks, such as video editing and games, should be running.

Migrating from your on-premises mailboxes to Microsoft 365 may look so overwhelming that you do not want to spend a pint of effort on it. However, you should go read the advantages you may gain when you let cloud computing systems take over your mailboxes. If you think that the process of migrating from IMAP or Exchange is daunting, find IT solutions providers…like us. Whether you are in Hudson Valley or not, Fisch Solutions is here to help you move.

Are you ready to migrate to Microsoft 365?

    If you need any assistance during your search for the perfect IT provider, do not hesitate to Contact Us! One of our friendly, knowledgeable staff members will be more than happy to assist you with your needs.

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