IF NOT EXISTS(SELECT * FROM sys.columns WHERE object_id = OBJECT_ID(N'[dbo].[CSAPP_SUPPORT_MAIL]')
AND name = 'CUSTOMER_NAME')
ALTER TABLE CSAPP_SUPPORT_MAIL ADD CUSTOMER_NAME VARCHAR(255) NULL

IF NOT EXISTS(SELECT * FROM sys.columns WHERE object_id = OBJECT_ID(N'[dbo].[CSAPP_SUPPORT_MAIL]')
AND name = 'CUSTOMER_EMAIL')
ALTER TABLE CSAPP_SUPPORT_MAIL ADD CUSTOMER_EMAIL VARCHAR(255) NULL