Hi,
Thank you for your answer, I think also that it became from lock, but I'll give you more details about my infrastructure. First, my nodes are all an instance of mailman-core only.
I have an existing MTA that handle all email, and sent them to a proxy, that dispatch all email between the existing pods. Then, email are transferred to the MTA and MTA send them.
I also have a custom webapp and API, that sent all request for managing a mailing list to the service that dispatch the request between all pods.
I don't use the archiver.
I only have one RDBMS that all pod use.
For the folder queue, I'm not sure if I should share this folder between all pods, because one instance of mailman core mean one worker if I'm right, and if that's the case, I want to have many workers because I will have high traffic. I don't know exactly how mailman-core manage its queue, but if you think that I can add this file in a persistentVolumeClaim, I'll try it :D