Just having another look at http://wiki2.dovecot.org/MailServerOverview , it seems to have some statements in it which are misleading, and some which are really ... well ... wrong.
Quote: "With the possible, optional, exception of the deliver MDA, Dovecot is not involved with reception, delivery, and storage of mail. That function is provided by a MTA such as postfix http://www.postfix.org. It is the MTA that determines where and how mail is stored - Dovecot must then be configured to retrieve the mail accordingly." (Entered by user "amfes".)
This contains a significant proportion of poppycock.
Dovecot includes extensive functionality for the storage (as in the action of storing) of e-mail as well as retrieval, in the shape of the LDA.
Using Dovecot's LDA is /required/ in the case of Dovecot-specific mail storage formats (sdbox, mdbox).
With mbox, use of the Dovecot LDA is advisable since it will guarantee a locking strategy which is compatible with Dovecot's mail retrieval functionality.
And in any case, use of the Dovecot LDA has merit in that it should guarantee line-up between the mailstore configurations used for storage and retrieval.
It is NOT the MTA that determines where and how mail is stored. It is the PERSON who configures the system who decides this, and codifies that configuration into whatever systems carry out local delivery and retrieval.
It IS true that use of Dovecot's LDA is optional, but to say that it is a "possible exception" is misleading. People /should/ use the Dovecot LDA if they are using Dovecot IMAP/POP, and the /option/ is to use the MTA's local delivery system /if/ it is so indicated on a particular system.
Quote: "Again, it bears repeating, Dovecot /is not responsible for mail delivery or storage/. Any questions on these issues involve your MTA and MDA. Get those working first." (Entered by user "DanielMiller".)
Again, contains quite a lot of misleading nonsense.
"Mail delivery" includes the hand-off of the message by the MTA to the LDA, and the storage of the message by the LDA. The LDA should probably be Dovecot, so really Dovecot /is/ partially responsible for mail delivery.
"Storage" involves that placing of message into the message store. This should be done by Dovecot, so Dovecot is responsible for this.
Bill