/var/www/html/xerxes-frontend/scripts/insertuser-mysql.sql

Define the password for mysql user mail by changing line 2 from:

INSERT INTO user (Host, User, Password, Select_priv, \ 
    Insert_priv, Update_priv, Delete_priv, Create_priv, \ 
    Drop_priv, Reload_priv, Shutdown_priv, Process_priv, \ 
    File_priv, Grant_priv, References_priv, Index_priv,  \
    Alter_priv) VALUES ('localhost', 'mail', PASSWORD('secret'), \ 
    'N','N', ...

to:

INSERT INTO user (Host, User, Password, Select_priv, \ 
    Insert_priv, Update_priv, Delete_priv, Create_priv, \
    Drop_priv, Reload_priv, Shutdown_priv, Process_priv, \
    File_priv, Grant_priv, References_priv, Index_priv, \
    Alter_priv) VALUES ('localhost', 'mail', \
    PASSWORD('<specify mail password>)', 'N', 'N', ...

You will need to remember the password you set for mysql user mail, for that is the password used to connect to the database.