Skip to content

Mailboxes (aka IMAP Folders)

INBOX is setup as the private inbox namespace. By default target/dovecot/15-mailboxes.conf configures the special IMAP folders Drafts, Sent, Junk and Trash to be automatically created and subscribed. They are all assigned to the private inbox namespace (which implicitly provides the INBOX folder).

These IMAP folders are considered special because they add a "SPECIAL-USE" attribute, which is a standardized way to communicate to mail clients that the folder serves a purpose like storing spam/junk mail (\Junk) or deleted mail (\Trash). This differentiates them from regular mail folders that you may use for organizing.

Adding a mailbox folder

See target/dovecot/15-mailboxes.conf for existing mailbox folders which you can modify or uncomment to enable some other common mailboxes. For more information try the official Dovecot documentation.

The Archive special IMAP folder may be useful to enable. To do so, make a copy of target/dovecot/15-mailboxes.conf and uncomment the Archive mailbox definition. Mail clients should understand that this folder is intended for archiving mail due to the \Archive "SPECIAL-USE" attribute.

With the provided compose.yaml example, a volume bind mounts the host directory docker-data/dms/config/ to the container location /tmp/docker-mailserver/. Config file overrides should instead be mounted to a different location as described in Overriding Configuration for Dovecot:

  - ./docker-data/dms/config/dovecot/15-mailboxes.conf:/etc/dovecot/conf.d/15-mailboxes.conf:ro


Adding folders to an existing setup

Handling of newly added mailbox folders can be inconsistent across mail clients:

  • Users may experience issues such as archived emails only being available locally.
  • Users may need to migrate emails manually between two folders.

Support for SPECIAL-USE attributes

Not all mail clients support the SPECIAL-USE attribute for mailboxes (defined in RFC 6154). These clients will treat the mailbox folder as any other, using the name assigned to it instead.

Some clients may still know to treat these folders for their intended purpose if the mailbox name matches the common names that the SPECIAL-USE attributes represent (eg Sent as the mailbox name for \Sent).

Internationalization (i18n)

Usually the mail client will know via context such as the SPECIAL-USE attribute or common English mailbox names, to provide a localized label for the users preferred language.

Take care to test localized names work well as well.

Email Clients Support

  • If a new mail account is added without the SPECIAL-USE attribute enabled for archives:
    • Thunderbird suggests and may create an Archives folder on the server.
    • Outlook for Android archives to a local folder.
    • Spark for Android archives to server folder named Archive.
  • If a new mail account is added after the SPECIAL-USE attribute is enabled for archives:
    • Thunderbird, Outlook for Android and Spark for Android will use the mailbox folder name assigned.

Windows Mail

Windows Mail has been said to ignore SPECIAL-USE attribute and look only at the mailbox folder name assigned.

Needs citation

This information is provided by the community.

It presently lacks references to confirm the behavior. If any information is incorrect please let us know! 😄