Question for you guys - what have you found as the best way to preprocess flat txt files to prepare them for SSIS? For example say the 3rd party vendor has issues with their files that don't follow the specifications, but it's to a point where it so common that you have an automated fix for it. However they are formating issues that break the SSIS Flat File Source object.
Examples: End of line format changing (CR vs CRLF), "NULL" appearing in numeric columns, delimiters changing (e.g. normally a pipe, but occasionally appear as commas instead).
The obvious solution for me was to write some C# to do preprocessing, but at that point you might as well do the whole thing in C# as it's inefficient to read the whole file in memory to prevalidate, then re-read it again to load it.