I think you're saying that you want mailing lists to be handled as a series, and old editions deleted automatically. And indeed, I've never seen that. But Fast

I think you're saying that you want mailing lists to be handled as a series, and old editions deleted automatically. And indeed, I've never seen that. But Fastmail has an "auto purge after x days" feature on folders, which comes pretty close in practice. You just need a rule that routes your mailing lists there. I use their email wildcards with my domain along with a convention of using a specific prefix to my address when signing up to mailing lists. Combined with OR rules for other individual from: addresses and most of my lists show up in one place and delete after 30 days.