Multi column support means that input files and output file(s) may contain lines consisting of several parts which are separated from each other by a comma or tab, "firstname.lastname@example.org,Bill Gates" for example. No mater how many parts each line in a file has. To determine the e-mail part of each line Opt-In List manager search for the first occurrence of '@' symbol. In the tools that provide multi column support feature there is an option named "Multi Column Support". By turning it on you can tell OILM to use this feature. However you should keep in mind, that use of this feature for lists, which contain only one column (one e-mail address in each line), can slow down their processing.