Office 365 migration Types

There are more than a few ways to achieve migration to Office 365 each with its own varying levels of difficulty. Let’s have a look at couple of migration options that we have in detail:

PST migration

One of the caveats of this type of migration is that it will require the IT administrator to be present physically onsite. On the bright side, one can utilize of the opportunity to make newer users accustomed to Office 365 environment while the migration process is on. Before proceeding further, do note that since IMAP only stores the mail headers and not the actual mail itself in most cases, it is recommended not to use PST migration when dealing with IMAP accounts.

How to get going?

First and foremost, ensure that users stop using their mails for some time. It would be better to redirect the mail flow using MX record at least a day before starting the migration – this ensures that no mail gets into a mail server that you no longer have access to after migration.

The next step would be to find out the location of PST files as they might not necessarily be in the default location. Have a look at this link to find out how. There can also be scenarios where you’ll look for PST files everywhere and end up finding nothing as cached mode has been kept disabled by the user. In all such cases you are more likely to find OST files and can make use of this guide to proceed further.

Ok so you now have the PST files with you. What next? Well the easiest and most straightforward way to import them into Office 365 would be to simply make a new Outlook profile as follows:

  1. Open Control panel
  2. Go to Mail
  3. Select show profiles
  4. Click Add
  5. Enter the details in the new profile wizard
  6. An empty mailbox will now be created, change the default mailbox to your Office 365 one.
  7. Now you can make use of the Outlook Import export wizard as detailed here to import mailboxes from the PST file
  8. mail-setup

IMAP Migration

For IMAP migration one has to create a CSV file to indicate the mailbox address onto which the contents of IMAP folder are to be copied. In addition, the CSV should also have the username and password of the original IMAP mailbox. You can use excel or even a simple text editor like the notepad to create .csv files. Given below is a sample csv format:


The first row, also known as the header row, of the CSV file lists the names of the attributes specified in the rows that follow. Each attribute name is separated by a comma. Every row under the header now serves to provide information about one individual user that will be used to migrate the user’s mailbox. The order of field values in the rows must be in the same order as that of the field names in the first row. Each value is separated by a comma.

Now open the Office 365 exchange control panel and follow the below steps:

  1. Click ‘+’ sign then select ‘Migrate to exchange online’ as shown
  2. From the window that appears select IMAP migration
  3. In the next window upload the CSV file and allow unknown column
  4. The subsequent window will ask you for IMAP server and authentication details. Provide the same and click next to start the process. Thereafter you will be able to view the progress and errors encountered from the top menu.

Fixing some common quirks

  • No contact? Well first remember that IMAP migration doesn’t include contacts, calendar or even tasks, better to use PST migration for such purposes. Having said that, make sure to check the ‘all folders’ list to see if you don’t have any other contacts folders.
  • Unable to move/delete items after IMAP import – use the MFCMAPI tool
  • Large mails not getting migrated – This is a limitation of IMAP migration as it supports mails of sizes upto 35 mb only.
  • PST import issues: This could most likely because of the corrupt PST files. You can try and use native recovery utilities like scanPST.exe or better yet use professional third party tools like EdbMails Outlook PST repair tool that can provide quick and guaranteed results .
  • There can also be instances where you run out of space in your Office 365 subscription, in which case you will need to upgrade the subscription or consider freeing up some space in the user’s mailbox.


Although the exhaustive guide above can help you achieve most if not all your migration goals, a more intuitive and least disruptive way of doing the same with minimal downtime would be to make use of the EdbMails Office 365 migration tool that is used by thousands of IT admins across the world to achieve seamless migration to Office 365.

Buy Now and avail Upto 75% plus off along with an Edb to PST, Edb to Office 365, Edb to Live Exchange Migrator license from EdbMails! Visit for further details.

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