ContributionsMost RecentMost LikesSolutionsRe: Error Handler for Validation Hi, When we write some data to a file we usually use some kind of a formatter (in the example above csv formatter ). All formatters are accumulating the input data, format the data and send to output. On the other hand the email snap it is not accumulating the data, it will send new email for every input document. If you want the email snap to accumulate all of the input data I suggest using Group by N snap and set the Group Size parameter to 0. Re: How to create a file only with the header? You should make sure that the Write CSV header is checked and Ignore empty stream is unchecked. Re: Change OBJECT to ARRAY using Mapper You can also use the sl.ensureArray($Name) expression. Using this expression you will make sure that the $Name object will be array.