Can I write a custom appender?
Yes. You can implement the log4net.Appender.IAppender interface to create you own customized appender. We recommend that you extend the log4net.Appender.AppenderSkeleton class rather than starting from scratch. You should implement your custom code in a assembly separate from the log4net assembly. To get started it is worth looking at the source of the log4net.Appender.TraceAppender as an example of the minimum amount of code required to get an appender working. To configure log4net to use your custom appender you need to specify the assembly qualified name of the appender type in the config file.