Mac Mail and Windows Outlook don't go along fine; and there's no reason they should. But it creates a situation for the users that wants to come from Mac Mail to Outlook. And even though you would it hard to count the total number of posts or articles that suggest the solution for the migration, you would also find it hard to count how many times these solutions don't work. Or worse, how many times they end up hurting the user because of the time they waste, how they corrupt the original files, and such.
I got an email yesterday asking for this same thing, and my mind reverted back to the past. I noticed I've been receiving such emails a lot of times and I always replied personally to these emails. Here I will take the time out to turn my reply into a public post.
Here's the excerpt from the email that refers to the question of backing up Mac Mail to Pst –
“...I ordered a new Windows laptop (HP) few days back and I am going to get it within a week. However, I have a Mac with right now with 'Mail' installed in it. I am going to give it away to my sister who will be going for her internship to another city in a day or two. I am thinking of all my offline emails in 'Mail' that aren't stored on servers. How can I keep a copy of them in my external hard drive so I can transfer them to Outlook once I got my Windows computer? I know Outlook uses Pst but I can't export the data to Pst files from the 'Mail'. Is there any way to backup Mac Mail to Pst?....”
Answer – The best way I've found to backup Mac Mail to Pst is to use “Mail Extractor Pro”. It is a very simple, light, easy to use, and highly efficient tool for converting everything in your Apple Mail to Pst format. The best thing about is that you will not lose any content or part of it when converting. Because if you go with any other methods that I have tried in past, you may end up with incomplete migration with data integrity issues.
“Mail Extractor Pro” doesn't let it happen. All of your attachments, images, folder structure, email properties, and every tiniest details with the data can be converted and kept as a backup on Pst files.
Furthermore, it is a very simple looking tool that is extremely light but works very fast. Its GUI is user-friendly and you don't need to know anything about how it works. As soon as you will look into it, you will know everything that's need to be done. You don't even need to export your Apple Mail data into Mbox, as with most of the other tools. “Mail Extractor Pro” can directly load up your “Mail” folder that contains everything and convert it to Pst straightway.
You can download the free trial version here that's limited with its number of items (ten) it converts to Pst from each folder inside Mac Mail. But the features and everything else is not restricted or locked. So you can properly evaluate it before paying for its full unrestricted license.
USL Software delivers email converter and email migration tools for its global customers.