We would like to set a custom subject to our serilog emails while using batching options. We configure our complete serilog within a json config file. The subject has always the default value, because apparently the input of the json is not currently parsed through a MessageTemplateTextFormatter. Our workaround is to manually build the logger in the code in the meantime. However, it would be great if this could be fixed. If you need further input, don't hesitate to reach out.