Email Storage Format

If your email is stored with the Mbox format and your Inbox is at or close to the 2GB limit then you will not be able to receive new emails. One solution is to move emails out of the Inbox to another folder or request to switch to the Maildir format.

What are Mbox and Maildir formats?
Two different methods for storing email messages on the mail server.

The Mbox format stores all your individual messages in a single text file. For example your Sent folder is a single text file that stores all the individual messages that you have sent.

Advantages:
1. Appending messages to a mail folder is fast
2. Searching for text inside a mail folder is fast

Disadvantages:
1. mbox is limited to 2GB in size for a file
2. Deleting messages from a folder is slow
3. Has file locking problems
4. Mail folders are prone to corruption

The Maildir format stores each individual message as a separate file. Again, we'll use your Sent folder as an example. In Maildir format your Sent folder is a directory on the mail server with each individual message stored under that directory as a single text file.

Advantages:
1. No 2GB size limit on mail folders
2. Locating, retrieving and deleting a specific message is fast
3. Immune to mail folder corruption

Disadvantages:
1. Searching for text within the message body can be slow

If you would like to switch to the Maildir format just send a request to help@engr.colostate.edu. Please read and understand the advantages and disadvantages of using Maildir format. For example if you do a lot of searching for text within email messages, then Maildir format might not be right for you. But if you are up against the 2GB size limit of Mbox format, then switching to Maildir format might be right for you.