Assume that you use Database Mail and sp_send_dbmail stored procedure with the @query and @attach_query_result_as_file option in Microsoft SQL Server 2014. The stored procedure run a query and set the result-set as an attachment of the email. When the query has a large result-set, the attachment is truncated to 64 kilobyte (KB) maximum.
The issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 4 for SQL Server 2014 /en-us/help/2999197
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.