I am running Thunderbird under RedHat. If I start Thunderbird using a specified profile (e.g., -P a1), it is displayed and fully functional using the settings for that profile. If I want to auto-compose a message, an application trigger will start another instance of Thunderbird with the same profile (a1) and the "-compose <compose args>" argument. This also works fine; I can select an addressee in the newly-generated message window, hit 'Send', and sent message appears on the original Thunderbird Sent folder. I need to run these within Docker containers. Scripts have been developed to support this and populate the container as needed. Thunderbird runs and functions normally within the container; messages are sent/received normally. However, when I try to launch another instance using the "-compose <args>" argument within the container, I get "Thunderbird is already running or not responding". If I do NOT have the first Thunderbird instance running, the "-compose" instance works normally; I can address and send the email. However, this forces me to close the main window everytime I want to auto-compose a message. It almost feels like the two Thunderbird instances are not communicating within the Docker container. Would appreciate any help/suggestions/debugging approach. Thunderbird version: 115.7.0 (I have no control over the version in use)