Converting your email from Thunderbird to Outlook can be a difficult task. The import tool in Outlook does not support Thunderbird mailboxes, and Thunderbird does not provide any export options. There are many free email conversion methods suggested in forum posts and blog articles, but they all have drawbacks.
In this article we review two free solutions:
These two free programs are then compared to the commercial version of Aid4Mail (see the comparison table).
Both free methods export Thunderbird mail to Outlook in three steps:
Our commercial version, however, can migrate email directly from Thunderbird to Outlook in one easy step.
We show that it is well worth spending a small amount (as little as $19.95 US) on a solution that can save huge amounts of time, does not require advanced technical knowledge, and most importantly gives accurate results.
The mbox2eml tool in IMAPSizeBroobles' IMAPSize is by far the most frequently mentioned free conversion solution in forums and blogs. However, as mentioned on the Broobles website:
"...the main purpose of IMAPSize is to locate space consuming folders and allow you to manage them."
In other words the program isn't primarily designed for importing email from Thunderbird into Outlook. In fact, it doesn't do that at all. IMAPSize simply splits mbox files into individual EML message files using its built-in mbox2eml tool. You then need to use another program to complete the procedure, usually Outlook Express or Windows Live Mail.Unfortunately IMAPSize doesn't maintain your mailbox hierarchy during its export. In Outlook Express or Windows Live Mail you will need to manually recreate your folder hierarchy, and then drag in the appropriate EML files, one folder at a time, from Windows Explorer. This is a manual task that can become extremely laborious and time-consuming if you have a lot of folders or a complex mail structure. Only then can you export your mail to Outlook using the Outlook Express or Windows Live Mail "Export Mail" tool.
IMAPSize does not recognize characteristics that are specific to Thunderbird like mailbox storage location, message status information, and detached attachments. So once the whole process is finished you will not be able to tell which emails have been read, replied, forwarded, or flagged – they all come up as read. Any attachments that were detached in Thunderbird will also be lost in Outlook.
You will need to compact your folders in Thunderbird before using IMAPSize otherwise you will find a lot of deleted messages, and messages that you have moved to other folders, appearing in Outlook. These irrelevant messages can often represent more than 80% of your email if your source mailboxes have not been regularly compacted.
So is IMAPSize a good solution? Well it works, sort of. And it's free (you can download the full version from the Broobles website). But unless you only have a few mailboxes to convert this may be a false economy.
On the other hand, if you have a lot of free time to spare, don't mind losing some of your data, and you are a technical person who knows what you are doing, then it may be the tool for you. But in that case we recommend Aid4Mail MBOX Converter. It's also free, but is easier to use and does a better job.
In conclusion, IMAPSize may well be good at its primary task of managing folders on an IMAP server but it is definitely not the best solution for transferring mail from Thunderbird to Outlook.
Benefits:
Disadvantages:
Screenshot of Aid4Mail MBOX ConverterAid4Mail MBOX Converter is a new freeware product from Fookes Software. It is designed to easily convert generic mailbox files to EML or mbox. The software offers a user-friendly wizard interface complete with context-sensitive help. The processing engine used in Aid4Mail MBOX Converter is taken from the commercial edition of Aid4Mail and so benefits from many years of development. As a result, it is fast, accurate, and very reliable.
Aid4Mail MBOX Converter can save you a lot of time compared to IMAPSize because it can restore your mailbox hierarchy during export to EML. However you will still need to manually recreate your folder hierarchy in Outlook Express or Windows Live Mail (as with other free solutions) and then drag in the appropriate EML files one folder at a time (from Windows Explorer). Note that you can avoid this potentially time consuming manual procedure by using one of the commercial editions of Aid4Mail.
As with IMAPSize, you then export your mail to Outlook using the Outlook Express or Windows Live Mail "Export Mail" tool. Unfortunately, message status information, like read, replied, forwarded, or flagged, is not preserved by the EML files drag-and-drop procedure.
The other big advantage Aid4Mail MBOX Converter has over IMAPSize, and other free solutions, is that it recognizes characteristics that are specific to Thunderbird. For example, mailbox storage location, trash folders, and deleted messages (including hidden unpurged mail). In addition, you do not need to compact your folders in Thunderbird before using Aid4Mail MBOX Converter.
Aid4Mail MBOX Converter is currently the best freeware conversion program on the internet. It is easier to use, faster, and more reliable than the others. However, as with other free programs, it only deals with the first part of the mail conversion process. You still have to manually transfer folders and EML files over to Outlook Express or Windows Live Mail, which can be a very time consuming task and does not restore message status information.
See our step-by-step tutorial to learn how to export Thunderbird to Outlook with Aid4Mail MBOX Converter.
Benefits:
Disadvantages:
Read more about Aid4Mail MBOX Converter or download your free copy now:
Aid4Mail is a dedicated email converter based on years of experience in the field of mail processing. As such it is not free (prices start at $19.95 US) but has the significant advantage of being able to export from Thunderbird to Outlook (and a host of other formats) quickly and easily, in one go, and with no loss of data.
With Aid4Mail you simply select Thunderbird as your source mail and Outlook as your target format, and press "Start" (see the step-by-step tutorial). It automatically restores your Thunderbird folder tree in Outlook without any manual intervention, and skips messages that should not be exported (messages that have been moved to another folder or deleted).
There is no loss of data with Aid4Mail. It correctly transfers the status information of your emails (like unread, replied, forwarded, and flagged) to Outlook, and successfully exports detached attachments. Aid4Mail supports Outlook 2003, 2007, and 2010, as well as older versions.
The table below shows how the commercial Aid4Mail compares with IMAPSize and Aid4Mail MBOX Converter:
| IMAPSize | Aid4Mail MBOX Converter | Aid4Mail | |
|---|---|---|---|
| Free |  |
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from $19.95 US |
| User-friendly wizard program with context-sensitive help |  |
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| Automatically finds your Thunderbird mailbox files | |
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| Can skip deleted messages and hidden unpurged mail | |
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| Dates of exported EML files conveniently match message dates | |
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| The EML folder structure matches your source mailbox hierarchy | |
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| Automatically transfers your Thunderbird folder structure to Outlook | |
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| Does not require time-consuming manual processing | |
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| Can export mail from Thunderbird to Outlook in one step | |
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| Converts mail status information like unread, replied, flagged | |
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| Pictures in the message body are correctly displayed in Outlook | |
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| Can restore detached Thunderbird attachments | |
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| Supports other mail formats | |
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Email conversion is a complex task with many pitfalls and no product is perfect. However, Aid4Mail is unmatched in its accuracy and retains more information during conversion than any of its competitors, both free and commercial.
Aid4Mail has a user-friendly wizard interface that helps you configure the export task step-by-step (see our tutorial on how to export emails from Thunderbird to Outlook with Aid4Mail), and there is a console version if you need to automate your migration. This makes Aid4Mail suitable for both small and large scale mail conversion projects, from home use to large corporate migrations.
Buy now, or download the free trial, and discover what Aid4Mail can do for you: