Maildir

The directory structure when the Maildir each user in the home directory is created

Maildir is a directory structure for storing and managing emails . Each e-mail is represented as a separate file in clearly defined directories. Maildir's storage concept manages without the use of complicated locking mechanisms, as the operating system can take care of this task completely due to the data structure.

Storage concept

In contrast to the mbox file concept and in contrast to the MH file concept , a maildir has at least three mandatory folders that are automatically processed.

1. tmp - This folder contains emails that are just arriving.
2. new - This folder contains incoming emails that have not yet been read.
3. cur - This folder contains incoming emails that have already been read.

Maildir's particular reliability is based on this clear separation. It was developed by Dan Bernstein and implemented for the first time with his qmail .

Maildir saves unlike other storage concepts, competing processes through locks to keep them in a queue. This is not only achieved through separate folders, but also through the creation of unique file names similar to a fingerprint. Each file name begins with the time it was created, followed by a period and a character string that is as unique as possible, and ends after another period with the host name of the sender. The middle string can consist of the Process ID and random numbers , for example . When the files reach the cur folder , their names are expanded by a colon and various flags that document their further use for a response and the like.

Maildir ++ is an extension of Maildir that supports MH-like additional subfolders and quota . It was developed by Sam Varshavchik and implemented for the first time with his Courier Mail Server .

Such sub- folders can be used for individual sorting or organization of e-mails, are arranged directly under the main Maildir folder , hidden by a leading dot in the name, and marked by empty files with the name maildirfolder . Each of these sub- folders contains and contains three sub- folders like the main Maildir folder . Nesting in one another is not intended, but any emulations using extended folder names with separators are optional. Additional files for automated mapping for IMAP have not been specified, but have been common practice since the beginning .

Programs

There is no need for coordination between mail servers and mail clients , and it is not possible to determine whether one or the other is using Maildir when they are connected using the usual network protocols for e-mail.

Both reference implementations have a modular structure and invite the widespread combination with and of special alternatives in the same file system . These include, for example, Postfix and Exim as well as Dovecot , which offer Maildir as an option.

Among the e-mail programs for or with Maildir for example:

• Wildebeest
• KMail
• Mutt
• evolution
• Mozilla Thunderbird (however not fully supported and possibly buggy)

Web links

• Benchmarking mbox versus maildir

Individual evidence

1. ↑ Using maildir format. Retrieved June 28, 2015 (specification from Maildir).  
2. ↑ Maildir ++. Retrieved June 28, 2015 (specification from Maildir ++).  
3. ↑ Choosing a Mail Back End . In: Gnus Manual . Free Software Foundation. Retrieved June 28, 2015.
4. ↑ ^{a b} Evolution / FAQ . GNOME Project. Retrieved June 7, 2011.
5. ↑ The Mutt Email Client . Michael Elkins. Retrieved June 7, 2011.
6. ↑ Thunderbird / Maildir - MozillaWiki. Retrieved April 26, 2017 (English).