%d expands to empty string
==========================

The problem is that your username string lost the domain part. Dovecot doesn't
keep track of the domain separately from username, so if something changes
username from "user@domain" to just plain "user", the domain is lost and %d
returns nothing. If you have 'auth_debug=yes', this shows up in logs like:

---%<-------------------------------------------------------------------------
Info: auth(user@domain.org): username changed user@domain.org -> user
---%<-------------------------------------------------------------------------

Below are some of the most common reasons for this.

Settings
--------

'auth_username_format = %Ln' lowercases the username but also drops the domain.
Use 'auth_username_format = %Lu' instead.

'auth_username_format' changes the username permanently, currently it's not
possible to make it affect only the authentication part.

SQL
---

'password_query' gets often misconfigured to drop the domain if username and
domain are stored separately. For example:

---%<-------------------------------------------------------------------------
# BROKEN:
password_query = SELECT username AS user, password FROM users WHERE username =
'%n' AND domain = '%d'
---%<-------------------------------------------------------------------------

The "username AS user" changes the username permanently and the domain is
dropped. You can instead use:

---%<-------------------------------------------------------------------------
# MySQL:
password_query = SELECT concat(username, '@', domain) AS user, password FROM
users WHERE username = '%n' AND domain = '%d'
---%<-------------------------------------------------------------------------

Or you can return username and domain fields separately and Dovecot will merge
them into a single user field:

---%<-------------------------------------------------------------------------
password_query = SELECT username, domain, password FROM users WHERE username =
'%n' AND domain = '%d'
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2011-11-16 14:09)