解決了

multiple Sent mailboxes, but it can be used to make sure that all of the different variants will have the same mails in them.

副作用

Unfortunately it also means that some clients will download the same mails to local cache multiple times.

原理:

on the filesystem level are symlinks to other mailboxes.

特性

The original mailbox can't be DELETEd while it still has aliases.

Mailbox can't be RENAMEd if it's an alias or if it has aliases.

Config

mail_plugins = $mail_plugins mailbox_alias
plugin {
  mailbox_alias_old = Sent
  mailbox_alias_new = Sent Messages
  mailbox_alias_old2 = Sent
  mailbox_alias_new2 = Sent Items
}

# Sent mailbox to be autocreated and advertised as SPECIAL-USE \Sent:
namespace inbox {
  mailbox Sent {
    auto = create # or subscribe
    special_use = \Sent
  }
}