I don't use configurations (Configuration files) in my packages, I develop and test them on my dev system and change any data source entries in the SQL job steps in...

WITH cte AS (
    SELECT...

WITH cte AS (
 SELECT t.N,SUBSTRING(@Str,N,1) AS [C],
   ROW_NUMBER() OVER (PARTITION BY SUBSTRING(@Str,N,1) ORDER BY t.N DESC) AS [RowNum]
 FROM dbo.Tally t
 WHERE t.N <= LEN(@Str))
SELECT TOP(1) C
FROM cte
WHERE RowNum...

A huge thanks for your reply Jeff.

Sorry for the delay in replying

1.
Approx 75% of current email adresses are between 20 and 30 chars but I will increase the size...

I have never used it but according to the spec referenced you are using the wrong quotes, you need to use single quotes as described and two of them within...