Dovecot based version of the mailserver.

Courier and Cyrus Sasl have been removed and substituted with Dovecot which now
handle authentication for Postfix, Imap and Pop3, with support for SSL.
This allow the use of several encryption schemes for the password as well as a
single user db.
OpenDKIM keys can now be provided at the startup and will be used instead of
generating new ones (so that you don't have to change your DNS configuration).

This version builds correctly on Docker but no integration tests have been
reworked to accommodate Dovecot instead of Courier and Cyrus Sasl. As such
at present no automatic tests can be executed.

README.md

@@ -9,7 +9,7 @@ Easy to deploy and upgrade.
 Includes:
 
 - postfix with smtp auth
-- courier-imap with ssl support
+- dovecot for sasl, imap (and optional pop3) with ssl support
 - amavis
 - spamassasin supporting custom rules
 - clamav with automatic updates
@@ -17,7 +17,6 @@ Includes:
 - opendmarc 
 - fail2ban
 - [LetsEncrypt](https://letsencrypt.org/) and self-signed certificates
-- optional pop3 server
 - [integration tests](https://travis-ci.org/tomav/docker-mailserver) 
 - [automated builds on docker hub](https://hub.docker.com/r/tvial/docker-mailserver/)
 
@@ -45,7 +44,7 @@ Before you open an issue, please have a look this `README`, the [FAQ](https://gi
       - ./spamassassin:/tmp/spamassassin/
       - ./postfix:/tmp/postfix/
 
-    # start he container
+    # start the container
   	docker-compose up -d mail
 
 ## Managing users and aliases
@@ -53,12 +52,22 @@ Before you open an issue, please have a look this `README`, the [FAQ](https://gi
 ### Users
 
 Users are managed in `postfix/accounts.cf`.  
-Just add the full email address and its password separated by a pipe.  
+Just add the full email address and its encrypted password separated by a pipe.  
 
 Example:
 
-    user1@domain.tld|mypassword
-    user2@otherdomain.tld|myotherpassword
+    user1@domain.tld|mypassword-encrypted
+    user2@otherdomain.tld|myotherpassword-encrypted
+
+To generate the password you could run for example the following:
+
+    docker run --rm -ti tvial/docker-mailserver doveadm pw -s MD5-CRYPT -u user1@domain.tld
+
+You will be asked for a password (and for a confirmation of the password). Just copy all the output string in the file `postfix/accounts.cf`.
+
+    The `doveadm pw` command let you choose between several encryption schemes for the password.
+    Use doveadm pw -l to get a list of the currently supported encryption schemes.
+
 
 ### Aliases