Further to MetaEd's answer about Dave Winer's February 1999 use of syndication, in September 1999 he mentioned a company called Vignette also involved in syndication:
So Vignette went the next step, and took the lead in what was then a new technology for the web, syndication. Last year they released a specification thru the W3C called ICE. With an ICE-compatible server, ZDNet could now publish their content, without ads, and sell republishing rights to portals. It was a clever business for Vignette, because it furthered dependence on their software, and if it caught on, it would create new customers for their software, the portals.
Diving into Usenet, we can find some December 1998 job ads from Vignette:
The
solutions will be centered around Vignette's products such as
StoryServer and Vignette Syndication Server and will involve
considerable integration with other products and
platforms in the Internet environment.
Winer mentioned The Information and Content Exchange (ICE) Protocol released through W3C and dated October 1998 that makes extensive use of the terms
syndication and syndicators. For example:
Abstract
This document describes the Information and Content Exchange protocol for use by content syndicators and their subscribers. The ICE protocol defines the roles and responsibilities of syndicators and subscribers, defines the format and method of content exchange, and provides support for management and control of syndication relationships. We expect ICE to be useful in automating content exchange and reuse, both in traditional publishing contexts and in business-to-business relationships.