How to split Mimecast archive exports by email account

Our Aid4Mail 5 Enterprise edition supports Mimecast SJF and EJF exports in their native format. It is able to process these potentially huge archives on-premises, fast and unattended.

Mimecast archives that were downloaded from the Mimecast server, via FTP, consist of a collection of ZIP files. These are organized by date range but not by email account. This means that, potentially, terabytes of mail belonging to many different users is all mixed together.

Aid4Mail Enterprise is able to split these huge archives and reorganize them by email account. As far as we are aware, it is the only product on the market able to do this.

Note that Mimecast archives that were delivered on an external hard drive are usually organized by user account so no further separation is necessary. However, you can use Aid4Mail to convert the archive to PST or another format.

Archive structure

Mimecast archives that were downloaded, and require separation by email account, typically contain a number of ZIP files whose names consist of date ranges. An example is shown below:

Inside each of the ZIP files is a complex folder structure of EML message files:

Split a Mimecast archive by email account

Mimecast archive exports can be extremely large despite being stored in compressed containers. Once split, the archive will no longer be compressed and will occupy even more space. Before starting, please ensure that your target location (where the split archive will be stored) contains sufficient free space. We also recommend you optimize Aid4Mail for speed.

Please follow the steps below to split a Mimecast archive by email account. It is assumed that you already have Aid4Mail Enterprise (or a trial version) installed and running.

  1. Create a new project in Aid4Mail.

  2. Enter a descriptive name in the Session name field of the Settings screen. For example: Split Mimecast archive.

  3. In the Source section of the Settings screen, set the following options:

    • Format: Select Mimecast from the drop-down list.

    • Files downloaded from Mimecast server: Check this. It lets Aid4Mail know what to look for in the folder hierarchy.

    • Location: Specify the full path to your Mimecast archive. This is the parent folder that contains the date-range ZIP files.

    • Remove journaling envelope: If remote journaling was used when the mail was initially sent to Mimecast, every email in the ZIP files will be “wrapped” in a journaling envelope. Turn this option on to remove the envelopes. Otherwise, you can leave it unchecked.

  4. In the Target section of the Settings screen, set the following:

    • Format: Select EML files from the drop-down list.

    • Location: Specify the full path of the folder where your separated mail is to be stored. We recommend that it’s not the same as your source location.

    • Folder structure: Select Use a template from the drop-down list.

    • Folder structure template: Specify a template that uses the {EmailAccount} token. You can use the token as-is or refine it to only match certain email addresses (read about how to do this in the Aid4Mail User Guide). In the example below, we have refined the token to only match addresses with an domain: {EmailAccount:*}

    • File name: You can use any of the options although we recommend FNV-1a signature as it tends to improve processing speed.

  5. In the main menu, select Settings > Options to open the Options screen. Choose the Filters tab. Under the {EmailAccount} template token heading, you can turn Strict behavior on or off.

    When off, the token matches email addresses found in the From, To, Cc or Bcc fields of the email header. When on, a match only occurs if the email address is also the owner of the email as determined by header metadata. This is explained in more detail in the Aid4Mail user guide.

    The main benefit of turning on strict behavior is that it prevents duplicate emails from being stored in a user’s folder, notably from mail sent to multiple recipients. However, as Mimecast archives typically don’t include outgoing mail, strict behavior may also prevent sent emails from being stored at all. Conversely, turning strict behavior off provides the sent emails but also the potential for duplicates. You may want to run tests with the option on and off to determine which best suits your requirements. We have found that most clients processing Mimecast exports with Aid4Mail prefer Strict behavior to be off (unchecked).

    Close the Options screen using the X at the top-right.

  6. In the main menu, select Session > Run. Alternatively you can select the Run button in the vertical button bar on the left side of Aid4Mail’s window. Aid4Mail will start processing the Mimecast archive.

Once Aid4Mail has finished processing, your target location should contain a folder for each email address that matched the {EmailAccount} token. Each of these folders contains the emails associated with that address. In our example, it looks like this:

Now that the archive is split by user account, you can use Aid4Mail to convert it to PST or another format. Please refer to the article How to convert Mimecast archive exports.

If you experience any issues, don’t hesitate to contact us. If you would like to buy an Aid4Mail license, please visit the Aid4Mail store.

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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