Either type the following at your terminal to add the catch all details for your domain to MySQL or use phpMyAdmin
# mysql -uroot -p mysql> USE vmail; mysql> INSERT INTO alias (address, goto, domain) VALUES ('your_domain.com', 'user1@example.com,user2@test.com', 'your_domain.com');
If using phpMyAdmin, navigate to the “vmail” table, then the “alias” table
and add a new row with the following details
address: yourdomain
goto: the email address you want to receive the catch all
domain: yourdomain