Can anyone help please??? I can't find a help article on this and need to migrate my email over to my new computer...

There's no standard process for this. I'd be looking for a "mbox to pst" converter, for which you may have to spend a small amount of money.

If the accounts in question are using IMAP, you probably don't really have a problem. You set it up on another computer and it just gets all your old messages from the server.

I'm no expert on macs but for expediency, it might be simpler to install Thunderbird on the new computer and then copy your old Thunderbird profile over to it. That gets all your old messages onto the new machine. You can then explore how to move your messages - for example, drag and drop may be possible.

Or you might see sense and realise that you don't really want to convert to Outlook after all. ;-)

Thank you very much for your post. But it doesn't solve my problem. I am still using a Mac (of course) but choosing to use Outlook instead of Thunderbird for exactly this reason (Outlook is much more robust, with better help support, more reliable than Thunderbird (which keeps messing with my emails that seem to "disappear" because the folder got corrupted somehow and it's a total mess now trying to find them all. Plus, Outlook offers very basic functionality that TB does not but absolutely should offer its users like exporting all emails in a folder hierarchy to different formats).

Does anyone have a suggestion on the best way to export my data into Outlook?

I have several Gigs of data that are POPped into my computer that I need to export in their folder structure. It would be a complete nightmare if I was to import all of my email - from 13 email accounts - into Outlook with no hierarchy.

Please help.

You don't think 'a "mbox to pst" converter' is a solution?

There is no standard interchange format for email messages, particularly when stored in folder systems. It's a game of two halves; one party must export and the other must import. There is no formal common ground, and so you are left looking for a utility that "knows" both mbox and pst formats.

I think a converter is a solution but I'm disappointed that TB does not provide that internally.

So is the only answer to this question that I must purchase a converter in order to transfer my email properly?

Well, exactly how many alternative email clients should Thunderbird support? We could say that if Outlook wants you to use them instead of Thunderbird they should provide a Thunderbird importer. It's not in anyone's interests to provide an export tool for their own email client.

Thunderbird has in the past offered an import tool to accept data from Outlook. This is currently broken and I can't remember whether changes in Thunderbird or changes in Outlook broke it. We do still support import from a few other email clients.

Well said! Thank you for your help.