I had the same issue when I tried to move emails from Windows Live Mail to Outlook. The primary problem was that Outlook doesn't let you import EML files all at once, which is a problem when you have many emails. At first, I tried to do it manually like drag and drop but that takes time and doesn't always keep the folder structure and attachments. That's when I started looking for an easy way to fix it. Softaken EML to PST Converter is one program that works well for me. It makes it easy to move EML files to Outlook. I was able to convert batch EML files into a single PST file without changing the formatting of the emails. Another best feature about it is that it works with EML files from several email platforms like Thunderbird, Windows Live Mail and others, so you don't have to worry about compatibility.
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