I have yahoo accounts for both personal use and office (firstname.lastname@example.org). How can I configure any of these accounts on Spark.
I think it is better to use Yahoo’s own client for this.
Do you even have an Openfire server? Then you can install Kraken plugin on the server, enable Yahoo gateway. Then, when you login to Openfire server with Spark, it should show Yahoo icon in the toolbar, which should allow registering with Yahoo service. But, Kraken is long time not in development, so it may be not compatible with Yahoo anymore.