Forum .LRN Q&A: Response to bug in bulk-mail and notifications with notification > 4k in size

The PL/SQL type is purposely set to varchar instead of clob. This is a trick that allows us to use clobs (> 4K) but treat them as varchars. We discovered this through a coding mistake.
FYI, a PL/SQL varchar is not the same as a SQL varchar (or varchar2), since a PL/SQL varchar may contain up to 32KB of text. As a general rule, a PL/SQL variable is limited to 32KB; to manipulate bigger data types, such as clobs, there are locator, essentially pointers to the actual data.