Aid4Mail Converter

Collect email from all popular mailbox formats and email services. Fast and accurate conversions at the tips of your fingers.

If you need a reliable tool to collect and convert emails, then you can’t go wrong with Aid4Mail Converter. It’s an ideal solution for preparing mail for ingestion into archival, eDiscovery, and forensics tools. The latest version of Aid4Mail is up to 6x faster! All popular mail services and file formats are supported.

Tasks frequently performed with Aid4Mail include:
  • Convert Microsoft OLM and OST files to PST
  • Export emails with their attachments to PDF documents
  • Collect mail from cloud-based accounts and save them to PST
  • Convert Outlook files to generic formats like EML and mbox
  • Merge Outlook MSG files into a PST file and vice-versa

To ensure security and mitigate any risk, all processing is done on-premises. It means you don’t have to share sensitive data with third-party providers and can save dramatically on processing costs.

Aid4Mail Converter clients include law firms, eDiscovery and litigation services, government agencies, schools and universities, IT services, NGOs, and banks. For confidentiality reasons, we do not disclose their names.

Next, we’ll explain all the key mail formats supported by Aid4Mail Converter. Use the shortcuts below to go directly to the section that is relevant to you:

Supported mail formats

Microsoft Outlook formats

Aid4Mail can access both local Outlook files and remote Exchange accounts. Local formats include PST, OST, OLM (Outlook for Mac) and MSG files. Exchange accounts can be accessed via an existing Outlook profile, the Microsoft Graph API or the IMAP protocol. Note that Microsoft email accounts like Microsoft 365 (formerly Office 365),, Hotmail, Live, and MSN all run on Exchange servers.

PST and MSG files can be processed with or without using Microsoft Outlook (MAPI). The option using Outlook is much faster and preserves more metadata (like email status information—read, replied, flagged). The option without has the advantage of not requiring an Outlook installation on your computer and can sometimes even process damaged files.

When converting to a PST file, you can set the maximum size for the file. On reaching this limit, Aid4Mail will automatically send the overflow to a new PST file with the same file name but with an index number added. For example, if you have 17 GB of mail and you’ve limited the PST file size to 5 GB, you will end up with four target PST files: The first three will each contain 5 GB of mail with the fourth containing the remaining 2 GB.

Note that target Outlook formats in Aid4Mail Converter are limited to PST and MSG files. If you want to migrate mail directly to an Exchange account, you will need our Enterprise edition.

Cloud-based accounts

Aid4Mail integrates a very robust implementation of the IMAP protocol. This gives you the ability to collect email from a large number of service providers including Gmail, Microsoft 365 (formerly Office 365),, Yahoo! Mail, AOL, GMX, and iCloud.

In addition, you can access any email account managed by popular IMAP server software like Dovecot, Courier, and Zimbra. Aid4Mail also includes support for the ProtonMail IMAP Bridge application.

You have the option of accessing Gmail accounts securely via the Google API and Exchange accounts (Microsoft 365, Hotmail, …) through Microsoft’s Graph API. Both of these methods rely on the secure OAuth 2 authentication protocol.

If you have access to an IMAP account via the FTP protocol, you can speed up email processing by downloading the account files locally. Aid4Mail supports files based on the Maildir and mbox formats. You can also speed up processing of Gmail accounts by using Google’s Takeout feature.

Note that Aid4Mail Converter only supports cloud-based accounts as a source format. If you need to migrate mail to a cloud-based account, you will need our Enterprise edition.

Local mailbox formats

Aid4Mail can extract mail from the following file formats:

  • Generic mbox files (mboxo and mboxrd variants)
  • Mozilla Thunderbird and SeaMonkey
  • Google Takeout mbox files
  • Maildir and EML files
  • EMLX files from Apple Mail
  • PST, OST, OLM and MSG Outlook files

Thunderbird and RFC 1521 emails with detached attachments are also supported.

Aid4Mail integrates a sophisticated mbox parser that is used to extract emails from Thunderbird, Google Takeout, and generic mbox files. It is able to handle a large variety of mbox and MIME format errors within the mailbox file. As a result, Aid4Mail can find emails that other products either miss or incorrectly merge with the preceding message.

You can export mail to mbox, EML, Thunderbird, SeaMonkey, PST and MSG, as well as archival and database formats (see next section).

During conversion, Aid4Mail can accurately restore the folder structure (including from labels in Takeout files) and email status information when available. This is rarely the case with competing products.

Note that Aid4Mail Investigator adds the ability to collect emails stored in disk images, forensically-extracted unallocated disk space, and mailbox files based on formats not officially supported. Aid4Mail Enterprise adds the ability to collect emails stored in archival files from Google Vault, Mimecast and Proofpoint.

If you need to process Outlook Express, Eudora, Pegasus or another legacy email formats which are not currently supported by Aid4Mail, please contact us to see if we have a solution that will allow you to process the email files.

Archival and database formats

Aid4Mail offers several special export formats. These can be used to archive mail, or for viewing messages without an email app, or as an intermediary format to import messages into a database.

The PDF format is probably the most popular in this category. It is used by law firms and professionals in the field of eDiscovery, auditing and litigation. You have the option to create archivable PDF/A, press-ready PDF/X, and standard “full” PDF documents. The message text is fully searchable in these formats. Options allow you to configure page headers and footers with page numbering, Bates stamping and other information.

Emails exported to PDF are rendered in rich text format, appearing as they would in a mail app. Attachments are stored separately in their native format, relative to the PDF file, and accessed through a link from the PDF document. You also have the option to embed attachments in the PDF document. Aid4Mail lets you create one PDF per email or merge all messages into a single PDF file.

If you prefer, you can use Plain Text as an alternative to PDF. Emails are converted to regular Unicode text (paragraph and character formatting is removed) and embedded contents (like pictures) and attachments are stored separately in their native formats. Your messages can then be opened for viewing and searching in any text editor, and take up less space than PDF files.

CSV (comma-separated values) and TSV (tab-separated values) formats are useful for viewing in Excel or for importing into a database program. Aid4Mail lets you configure the contents, including metadata and the message text. If you choose to include email attachments, they are stored separately in their native format and their file location is added to the delimited data.

The XML format is typically used for long-term archiving. It is a popular solution with national libraries. As with CSV and TSV formats, you can decide which metadata to include in the XML file; attachments are stored separately in their native format and links to them are saved in the XML file.

Finally, with the HTML format, emails can be viewed in any web browser and rendered as they would in a mail app. Attachments are stored separately in their native format, relative to the HTML file and accessible from the email message.

Aid4Mail enables you to customize the HTML data and offers a convenient viewer. You can filter emails by folder and keywords. Keyword filtering is based on matches in the date field, subject line, sender and recipient.

Lots of helpful features to ease your work

Aid4Mail 5 is a complete rewrite of our software. We’ve made it faster, even more reliable, and integrated many features that users have requested over the years. It has a modern and user-friendly interface with local context-sensitive help to assist you throughout your project. The GUI includes accessibility features such as Windows high-contrast mode, zoom and keyboard-only navigation.

When setting up your conversion, you can choose to process all emails from your source format, or select specific folders. Aid4Mail displays your folder tree in a way that resembles what you see in your mail app. So excluding or including folders is as easy as checking or unchecking the corresponding box. Note that Aid4Mail Investigator and Enterprise offer full-fledged email filtering with the ability to query the contents of message text, attachments and metadata.

Incremental processing can be activated with one click. This feature can save a lot of time to continue a prior conversion where you left off, or capture new mail received since last time.

During processing, Aid4Mail provides detailed progress information, statistics, error messages and multiple logs. You’ll also get an estimate of how long a task will take to complete.

Another valuable feature is the automatic removal of binary duplicates, with the same file name, created in the target folder. This feature works with EML, Plain text, HTML and PDF files as well as extracted attachments. Files with the same name but different contents are preserved by adding an incremental number.

We’ve also developed a free remote authentication tool. It enables anyone to grant temporary access to their Microsoft 365, Gmail or IMAP account. This can be done securely, without providing login credentials, and without an installation of Aid4Mail. Download this article for more details.

If you need to process journaled emails from an email retention or archival system, Aid4Mail can remove the journaling envelope. Doing so gives you access to the original email without the extra journal wrapper and its metadata.

Using our flexible folder and file naming feature, you can split or merge mailboxes. Or better still, reorganize emails according to specific criteria like email address, sent date or status flags.

Speed matters

If you need to convert a large amount of mail, processing speed is really important. We have focussed on optimizing the Aid4Mail code and algorithms to ensure the best possible performance. And the results show! Compared to our competitors, you can expect Aid4Mail to complete a conversion 6 to 10 times faster with local file formats.

In one of our tests, Aid4Mail converted 98,051 emails (9.97 GB) from Thunderbird to Outlook PST in just 12 minutes and 34 seconds. That’s 130 emails per second!

Going from PST to mbox with the same data is a bit slower—taking 29 minutes and 23 seconds to complete. That’s just under 56 emails per second. The difference in speed is due to extra processing done by Aid4Mail to improve conversion accuracy. Nevertheless, this is considerably faster than other products.

Processing speed was tested on a 7-year old desktop PC with an Intel Core i7-5930K and an SSD drive. So expect even better performance on the latest generation of high-end computers.

We’re not including test results from remote accounts because Internet speed, service bandwidth throttling and protocols are the main performance bottlenecks. Instead, we recommend that you run your own tests with our free Aid4Mail trial.

Some of our users process several terabytes of email data on a regular basis. For these clients, the speed gain from using Aid4Mail is enormous. A task that will take a competing solution a couple of weeks to complete may take as little as a day or two with Aid4Mail.

Accuracy matters too

High processing speeds are only beneficial if the conversion is accurate. Again, Aid4Mail stands out from the competition.

Email conversion is a complex task with many pitfalls and no product is perfect. There are several reasons why:

  • Many mail apps use proprietary storage formats that need to be reverse engineered. This is a difficult process involving assumptions and usually lots of testing.
  • Some apps and services provide access to email accounts through complex and often poorly documented APIs.
  • Bugs in email programs can result in corrupted mailboxes. Errors in APIs can affect the reliability of data collection. Sometimes developers don’t respect email (RFC) standards.

Common pitfalls include:

  1. Message text

    Non-Latin text, special characters and symbols are displayed with incorrect characters or substituted with question marks. HTML code and other types of encoding are visible instead of being rendered for reading. In some cases, these display issues cause the message to be illegible.

  2. Images and attachments

    Embedded images and attachments are missing. Images can also lose their context within the message and become regular attachments.

  3. Email metadata

    Sender or recipient names are displayed but the email address is missing. The message date is lost or showing the conversion date instead of the sent date. Email status information, like Read, Replied, and Starred, is missing. Other metadata, like the origin and server relay information of incoming messages, may be lost too.

Whether you’re migrating company accounts or collecting email for a legal case, it’s important that you choose a solution that minimizes data loss. This requires a high quality solution.

We’re perfectionists and have worked hard to reduce conversion issues. Over the years, we have compiled a treasure trove of problem files that we regularly use during testing. This has helped make Aid4Mail one of the most reliable and accurate email converters on the market.

Flexible licensing options

Aid4Mail licenses allow you to process an unlimited number of mail accounts and files, whether in-house or external. You can purchase a one-year license, or three years at a reduced price. During the license validity period, you benefit from free software updates and our legendary customer support.

On purchasing a license, you will receive an activation code that gets you up and running with Aid4Mail within minutes of making your payment. Once activated, trial mode is turned off and your license becomes tied to your computer and Windows login account. See our EULA for details on how this works.

If you need to run Aid4Mail on a computer that doesn’t allow Internet access, simply contact us for an offline activation code. There is no charge for this option but it offers less flexibility than online activation.

We also offer licensing options for running Aid4Mail in a virtual environment. Pricing is determined by the number of concurrent users plus the total number of users and installations. Contact us for a quote.

If you’re ready to buy an Aid4Mail license, visit our Pricing page for pricing details and links to our online store.


Make sure you also check the extra features included in our other products. Aid4Mail Investigator adds native pre-acquisition filtering and powerful search queries, the ability to access unpurged emails as well as email carving from disk images and unallocated space. Aid4Mail Enterprise adds all of this plus support for Google Vault, Mimecast and Proofpoint archives along with cost-effective licensing options for teams.

Why choose Aid4Mail?

We have been developing software since 1990. Our first email tool was launched in 1999 and Aid4Mail followed in 2005. So our experience in processing email data spans over two decades.

All core functionality in Aid4Mail is developed in-house. This means that key features are tightly integrated and optimized for speed. We are in full control of our code, including major components like email parsing and conversion, the filtering engine and its search syntax, MAPI access to Outlook accounts, and even the IMAP protocol used to connect with services like Yahoo! Mail and AOL.

Important clients around the world are relying on our software. These include the US government and law enforcement agencies, top law firms, national libraries, prestigious universities, major banks, and international NGOs. Currently half of the Fortune 50 companies are Aid4Mail clients and the numbers keep growing. For confidentiality reasons, we do not disclose their names.

Try it out for free-no strings attached

There’s lots more in Aid4Mail Converter, and the best way to discover its capabilities is to try it out. We offer a free trial version with no time limit, no forms to fill-in and no obligations. Simply visit our Downloads page to get your free trial now.

And if you would like to see a detailed feature comparison between the three Aid4Mail editions, check our Aid4Mail 5 feature comparison table in PDF format.

About Fookes Software

Fookes Software Ltd
La Petite Fin 27
1637 Charmey (en Gruyère)

For over 25 years we have been developing award-winning tools and productivity software. We also have more than 20 years of expertise in the field of email processing and analysis.

Our clients include Fortune 500 companies, government agencies, law firms, universities, and professionals specializing in e-discovery and forensics from around the world.

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