Yep, that's the new "dlist header file" format. And you're right, we should
document it!
It appeared with this commit:
commit 29bce1f64de17e108adef0f814a3165888ca06a5
Author: Ken Murchison <mu...@fastmail.com>
Date: Thu Oct 25 14:24:13 2018 -0400
mailbox.c: use dlist to store cyrus.header data, including mboxname and
mbtype
And it was changed because the old format was very hard to safely extend.
DLIST is a Cyrus internal format that I first wrote for the new replication
engine in 2.4, back in 2010. It's not as efficient as JSON and I'm kind of
tempted to move to JSON - but it is very similar to IMAP list syntax, so it was
easy to build tooling for.
Bron.
On Thu, Sep 18, 2025, at 17:56, s...@spi.cz wrote:
> Hi,
>
> I noticed a difference in the format of the cyrus.header file. Older files
> correspond to the specification according to the documentation:
>
> <Mailbox Header Magic String>
> <Quota Root>\t<Mailbox Unique ID String>\n
> <Space-separated list of user flags>\n
> <Mailbox ACL>\n
>
> e.g.
> user.such^such^cz cu3zc27vvohouoi31e513ii2
>
> such.such.cz lrswipkxtecdan cyrus lrswipkxtecda
>
> However, in current files, information about user flags and ACL is on a
> single line, e.g.:
>
> %(T el N user.such^such^cz.Linkedin I 5rhsan0cost2tdsgd2g2vt3s Q
> user.such^such^cz A %(such.such.cz lrswipkxtecdan cyrus lrswipkxtecda) U
> (NonJunk $NotJunk NotJunk $Forwarded JunkRecorded $J
> unk Junk))
>
> Since when and why is it now created this way? And why isn't it in the
> documentation?
>
> regards
>
> Milan
> *Cyrus <https://cyrus.topicbox.com/latest>* / Info / see discussions
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--
Bron Gondwana, CEO, Fastmail Pty Ltd / Fastmail US LLC
br...@fastmailteam.com
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