NOTE: This comment is for reference only.

mail_location setting was split into multiple individual settings, where we use mail_driver + mail_path.

Documented in Dovecot 2.3 => 2.4 changes required for DMS under General mail settings: #4447

As my issue on the Dovecot migration detailed (and a related user comment), the shorthand vars like %d and %n are not valid anymore.

NOTE: The comment change is a bit incomplete to suggest via the GH web UI diff suggestion above, as the whole comment block probably needs to be revised for Dovecot 2.4.

• Mailbox root detection seems to rely on scanning fixed paths unless explicitly set via mail_path (previously derived from a substring of mail_location in Dovecot 2.3).
• While our docs (and tests) have some mention of mbox support, Dovecot has more visible deprecation warnings of it's support and it's "mail location" section likewise discourages it in favor of dbox or our DMS default, maildir.
• That block comment is about mbox, and I don't think we really see much user engagement about it's usage so I think it's safe for us to drop any support of such officially on our end 🤔

NOTE: While we're only configuring mail_driver + mail_path here, it seems that mail_path can be absolute or refer to mail_home as a base/prefix via ~ (which Dovecot 2.3 also supported via %h), as is shown in the Dovecot 2.4 Quick start example:

mail_home = /srv/mail/%{user}
mail_driver = sdbox
mail_path = ~/mail

mail_path docs insist on an absolute path, and I assume the ~ syntax for mail_home as a prefix is still considered an absolute path in that sense.

Contrary to advice there for mail_path to be a subdirectory, we seem to have configured the inverse by having mail_home refer to a subdirectory instead:

mail_home = /var/mail/%d/%n/home/
mail_path = /var/mail/%d/%n

instead of:

mail_home = /var/mail/%d/%n
mail_path = ~/mail

Too late to mess with that though 😓

TODO: mail_home will also need to be updated as well due to usage of the shorthand vars:

mail_home = /var/mail/%{user | domain}/%{user | username}/home

While %{user | username} is desirable, it is not a migration specific change but rather a separate bug fix to consider. As you'll notice we had %u (aka %{user}) not %n (aka %{user | username}), but since this field should be set already I think in this case it may be fine.

Possibly been an issue in DMS with LDAP I think (fairly sure I've seen a problem somewhere, but I'm also not sure if the setting here is assumed to be the prior setting). Might need to consider deferring the change to a separate PR with changelog entry 🤔

NOTE: This comment is for reference only.

Documented in Dovecot 2.3 => 2.4 changes required for DMS under AUTH subsections PassDB + UserDB: #4447

I was unable to find context for why this was no longer available in existing Debian 13 changelog/notes 🤔 Seems odd, perhaps it'll return upon actual release 🤷‍♂️

I found that strange too, but it is still missing in the latest trixie-slim image.