Maildir vs MBOX - How do they Differ?

If you are a user who wants to know the difference between mbox and maildir formats then follow this article. In this blog, we are going to tell you about the difference in Maildir vs MBOX format.

Maildir and MBOX are just the email formats that used to store the messages in email applications. First MBOX acts as a mail storage system on a cPanel server but at this time Maildir is the default option. MBOX puts all messages on the server in the same file, while Maildir stores messages with unique names in individual files.

Let us talk about Maildir vs MBOX in detail-

Maildir vs MBOX Format


The file format of the mailbox is also known as Mbox. Mbox is a type of email file that stores messages in plain text format. The file's email content consists of 7-bit ASCII text and the remaining email components (attachments, metadata, etc.) are stored in encoded form. All email messages are stored on the account mainly inbox, in a single file.

MBOX Benefits-

  • Universal file format support.
  • It's easier to add new mail to the mailbox.
  • It's easier to check for text in the mailbox.

When used with network file systems, it has some file locking issues and problems.

Using the MBOX server, if the server is configured then into the inbox file, messages will be written by Exim on the appropriate mail account. Exim will create a file in the appropriate directory structure of the mail account if the server is configured as a Maildir server. Exim works in a single format only.

Using a cPanel script, you can convert MBOX to Maildir format. You can use the following script to modify the file format for users who want to move the data into cPanel and WHM servers. Login via SSH to the server and execute the following command:


Wait for its completion(may take 24 hours). It can vary depending on the hardware of the servers and the number of accounts to be converted. The user is unable to send emails when the server is in the process of conversion. Overt the file format in off-peak time is recommended. After executing the instruction, you can see the following options:

Start maildir conversion process with Courier mail server

Start maildir conversion process with Dovecot mail server

(*) Exit

The first alternative used by Courier as the mail server to migrate the server from MBOX to Maildir storage format.

Second option used with Dovecot as the mail server to migrate the file from MBOX to Maildir storage format.

The third option (*) is used or exiting the script.


New subdirectory: Both incoming email messages received in a limited time are each stored in a new subdirectory. It is used to send a new message to the recipient. The file update time in the new directory is the message's delivery date. The message is typically in RFC 822 format, beginning with a line "Return-path" and a line "Delivered-to."

Cur subdirectory:The cur directory files are similar to the current directory, but the cur files are no longer new mails. They were interpreted by the mail reading program of the recipient. That is, it only saves messages that the user has read.

Tmp subdirectory:tmp directory contains a temporary Maildir file extension directory data file. It is used to ensure that the message is delivered efficiently.

Maildir Benefits-

  • More stable and faster than MBOX.
  • This file format's main advantage is that it can easily be marked as subdirectories.
  • It filters and transfers in the respective subdirectories when a new message arrives.
  • No compatibility issues, these files can be transmitted over the network.
  • Compatible with mail servers from both the courier and the dovecot.
  • The safest format and the least chance of manipulation of results.
  • For each incoming mail, the Maildir directory generates a single file.


We have talked about the Maildir vs MBOX format differ from each other in this blog. If you want to access MBOX files but you are not able to open that then you can use an MBOX Converter utility. Also, if you want to migrate Maildir to other file formats then you can use Maildir Converter that quickly converts Maildir to other desired or preferred formats.