Do we need fine-tunable `delete_server_after` at all?

[Simon-Laux]

also for another issue, i am wondering if we need fine-tuneable delete_server_after at all - only important thing seems to be that for non-chatmail, one probably does not want to have everything deleted

Originally posted by @r10s in #7631

[Simon-Laux]

i am wondering if we need fine-tuneable delete_server_after at all

I guess that leaves 3 options:
A: delete immediately (no multidevice)
B: delete after Time X (classical email + multidevice)
C: off (dc client does not delete from server)

• automatic for chatmail
• never for classic email

Though I don't see much harm in allowing users to keep choosing some custom duration for B, so they can customize it, like if they have one device that is seldomly online they could benefit from longer retention, while still clearing up space on their classic email account eventually.
But on the other hand we may want to find a real solution for the multidevice usage (where one device is seldomly online) anyway, which also works with chatmail, like syncing old messages over iroh when both devices are online.

[iequidoo]

A: delete immediately (no multidevice)

Should be "no multi-device and backups" at least, but it's better to always allow choosing options other than "immediately", there are also unencrypted messages which you can read using another client (this is not always "shared usage", e.g. the user can uninstall Delta Chat and see messages in webmail), even encrypted messages it may make sense to store on the server if keys are somehow exported.

I think that at Core level it's better to allow fine-tunable delete_server_after even for chatmail, the chatmail auto-deletion logic is unrelated to Core and it's better to have less is_chatmail checks. I.e. UIs should decide what options to show.