Each email migration can be divided into two parts; there is a manual and direct method. The transfer of emails from EML to Office 365 in the same way, can also be accomplished in two parts. After reading this article, you may decide which method you would like to adopt. With the manual method being free but it is always a big and time-consuming process since using 3rd party solution makes EML to Office 365 migration easy and secure. Before moving to the migration method, I am going to discuss a little bit about the .eml file format.
What is the EML format and where it is commonly used?
An EML file saves data in RFC 822 standard format. EML file extension is usually used in several email clients that allow you to open EML files such as Thunderbird, Entourage, Apple Mail, Window live mail & Outlook Express, etc.
How to Export EML Files from Different Email Clients?
Exporting emails as .eml files from different email clients is not a tough part for the user, yet I would like to explain. If you want to export EML data from Thunderbird, WLM, Outlook Express, then select your email and export it to any new folder using the drag-n-drop method easily.
Manual Approach
If you have a small size of EML data then it may be helpful for you. This method is also a combination of two parts:
(a) Convert EML to PST format
(b) Retrieve PST from Outlook
(c) Import PST into Office 365 using Network Upload Method
Export EML to PST format
Before starting the conversion, we will need to install WLM. Because MS Outlook allows you to import WLM files or Window Live Mail supports EML extension.
If you are already using WLM then you can follow the below guidelines otherwise use the Drag & Drop method to import EML data Window Live Mail then continue ahead.
• Open Window live mail >> Go to Export email >> Choose “Export messages”.

• Select “Exchange Server” then press Next >> Confirmation window appeared to click on yes button

• Choose your EML data folder >> At last press the Ok button
• After uploading EML files to Outlook, we again perform to export PST via Import and Export wizard.
Export PST file from Outlook
• Open MS Outlook >> Go to file tab >> Select “Import & Export wizard”.

• In Appear window select “Export a file” >> Choose “Personal folder file” (.pst) then Next >> Choose your imported EML data

• Browse your save location destination anywhere you want
• Put a password if you want otherwise press Ok
Once the conversion is complete, we can use the Network Upload Method. This process is also very long and with some good technical knowledge required to execute this PST upload method.
Network Upload Method
In this process, first, we will install the Azure Azcopy tool and copy SAS URL. This SAS URL is very confidential for every organizer because it stores the location of the Azure Azcopy Tool and the Cloud Storage SAS key, which provides the permission to upload the PST file.
To explore the Network Upload Method go here: https://docs.microsoft.com/en-us/office365/securitycompliance/use-network-upload-to-import-pst-files
An Alternative method for Importing EML Files to Office 365 Mailbox
Due to a lot of drawbacks and time-consuming processes, users avoid using manual methods and choose a third-party solution. Because this method is embedded with many excellent features that make it quite easy. Here you do not need to import EML data repeatedly. Once you add EML files, follow three easy steps (Load, Preview, Export) and your file will be uploaded to Office 365.
MailsDaddy EML to Office 365 migration tool is specially designed to import multiple EML files to Office 365 at once. It is able to transfer EML data to Office 365 mailbox directly, without having to save your login credential. With this tool, you can easily export EML files in Office 365 without harming or losing any kind of data infrastructure, properties, and Metadata like Cc, Bcc, To, From, Subject, etc.
Final words
Everyday users are moving their emails to a better platform. In Office 365 is the best option for enterprise or business users. Since, Office 365 allows you to access valuable data from anywhere through laptops, desktops, mobile, tabs, etc. So use the above tool and import EML files to Office 365 or Exchange online. If you have any query then leaves a comment.