The normal graylisting with postgrey store the whitelist in a berkeley database which needs to be replicated on a mailserver cluster. With sqlgrey you can do that replication with a mysql database.

First create a Database “sqlgrey” with an user “sqlgrey” on your database server. (The tables will be created by sqlgrey.)

1. Install sqlgrey:

aptitude install sqlgrey

2. Edit the sqlgrey configuration file:

vim /etc/sqlgrey/sqlgrey.conf

Edit the database settings:

## Database settings
db_type = mysql
db_name = sqlgrey
db_host = YOUR_DATABASE_SERVER
db_port = default
db_user = sqlgrey
db_pass = YOUR_PASS_WORD
db_cleandelay = 1800
clean_method = sync

4. Add sqlgrey to the postfix configuration:

vim /etc/postfix/main.cf

Append the recipient restrictions:

smtpd_recipient_restrictions = permit_sasl_authenticated,
permit_mynetworks,
reject_unauth_destination,
reject_unknown_client,
reject_invalid_hostname,
check_policy_service inet:127.0.0.1:2501,
permit

5. Restart the services:

/etc/init.d/sqlgrey restart
/etc/init.d/postfix restart

6. Controll

Watch the content of the table “connect” it contains the sender information of every incoming mail.