question: protected void mapRecipients ( Map < MailAddress , String > recipientsMap ) throws MessagingException { Connection conn = null ; PreparedStatement mappingStmt = null ; Collection < MailAddress > recipients = recipientsMap . keySet ( ) ; try { conn = datasource . getConnection ( ) ; mappingStmt = conn . prepareStatement ( query ) ; for ( MailAddress recipient : recipients ) { ResultSet mappingRS = null ; try { mappingStmt . setString ( 1 , recipient . getLocalPart ( ) ) ; mappingStmt . setString ( 2 , recipient . getDomain ( ) ) ; mappingStmt . setString ( 3 , recipient . getDomain ( ) ) ; mappingRS = mappingStmt . executeQuery ( ) ; if ( mappingRS . next ( ) ) { String targetString = mappingRS . getString ( 1 ) ; recipientsMap . put ( recipient , targetString ) ; } } finally { theJDBCUtil . closeJDBCResultSet ( mappingRS ) ; } } } catch ( SQLException sqle ) { throw new MessagingException ( "Error accessing database" , sqle ) ; } finally { theJDBCUtil . closeJDBCStatement ( mappingStmt ) ; theJDBCUtil . closeJDBCConnection ( conn ) ; } }
target:  Map any virtual recipients to real recipients using the configured JDBC connection, table and query.