Remove `show_emails` option

[link2xt]

This option is already marked as "legacy" in 2.33 releases of Delta Chat.

There is a plan to drop show_emails, mvbox_move and only_fetch_mvbox options as they all are only useful for unsupported "shared mailbox" usecase.

Removing show_emails will also make it easier to do #7494 as we will then have only one option that affects which messages are processed.

Related issue is that UIs hide this option but somehow allowed to set it to non-default value in the past and it prevents users from adding relays: #7622

I opened a PR for removing the option: #7632

Before removing the option we also need to warn users one release in advance with a device message or UI banner in the settings screen like Delta Chat for Android does when you disable permanent notification in F-Droid version. If we just remove show_emails option, then single-device setups that are configured to delete chat messages immediately will start deleting non-chat messages immediately and eat incoming mails that were previously skipped.

[Simon-Laux]

deleting emails is quite more serious than I thought this could get. we probably need to unset the deletion setting and then inform user in device message.
I think it would make sense to remove all those unsupported options at once, but make sure the user gets a state that doesn't delete all their normal emails. And after changing they would get a device message that explains the changes and links to some forum post that goes into more details:

• you were likely using shared mailbox with other email program, this usecase is not supported anymore
• we recommend chatmail or using your dedicated email account only with deltachat (maybe link guide to use multitransport to migrate away from shared mailbox)
• if you enabled auto deletion from server, then we also disabled that, so that your existing normal emails are not deleted by accident. once you migrated you can enable it again.
• read more at <forum post>

[link2xt]

There is not only delete_server_after setting, but bcc_self which in case of chatmail means "delete at once" if it is disabled. UIs currently hide delete_server_after when is_chatmail is set.

We want bcc_self to be off by default and result in immediate deletion of incoming messages in case of chatmail as otherwise chatmail relays need much more storage to support single-device users. On the other hand we don't want "use classic email as relay" option to result in a setup that eats your mail, so it should have a warning there that this will start eating your messages immediately.

[Simon-Laux]

so it should have a warning there that this will start eating your messages immediately.

the warning should be inconvenient to skip, like make the user wait for a countdown before they can press continue.

[iequidoo]

If we just remove show_emails option, then single-device setups that are configured to delete chat messages immediately will start deleting non-chat messages immediately and eat incoming mails that were previously skipped.

This apparently means that we should unset delete_server_after and inform the user about that, and bcc_self shouldn't result in deletion of non-chat messages (but it's probably ok to delete encrypted ones as we don't support key import anymore). Currently the delete_server_after default depends on bcc_self, but this should only be so for encrypted messages.

[r10s]

the warning should be inconvenient to skip, like make the user wait for a countdown before they can press continue.

instead of doing UI stuff like that, better go for the other proposal from @Simon-Laux above:

• set delete_server_after to "Off" at the same time where we remove show_emails
• if either delete_server_after or show_emails was used, add a device message explaining that emails are no longer deleted automatically from the server and that all emails are shown now

i totally agree, that we should remove mvbox_move and only_fetch_mvbox as well soon, to not have an endless discussion about that. but that can be another issue/PR then. ftr, i am using one delta account together with thunderbird in the now unsupported shared usage, and it works okay without "Move to DeltaChat folder" - i move the files with thunderbird now, detection by "[...]". @webratte reported in a chat, that filtering by To: hidden-recipients worked for him. so, there are still options, it is just that one has to hack them to the other apps, no longer to Delta Chat :)

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

[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.