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Mention the concern of mdbox mailbox format.

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Zhang Huangbin 2018-12-21 22:45:11 +08:00
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commit 9c1eb34b95
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en_US/howto/change.mailbox.format.md
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# Change per-user mailbox format (e.g. maildir, mdbox)
iRedMail uses `maildir` mailbox format by default, it's easy to migrate and
maintain, but if mailbox size is growing, the performance will be getting
slower due to too much disk I/O. Dovecot's own mailbox format `mdbox` has very
good performance for large mailbox due to reduced disk I/O.
iRedMail uses `maildir` mailbox format by default, it's easy to backup, migrate
and recover. As long as mailbox grows larger and larger, the performance will
be slower due to too much disk I/O - caused by `maildir` format. Dovecot's own
mailbox format `mdbox` has very good performance for large mailbox due to
reduced disk I/O.
You may want to switch to other mailbox format for some reason. To help you
switch easily, iRedMail-0.9.9 introduces 2 new SQL columns (for SQL backends)
and LDAP attributes (for LDAP backends) to help you switch per-user mailbox
format easily. All [mailbox formats supported by
Dovecot](https://wiki2.dovecot.org/MailboxFormat) are supported in iRedMail.
Dovecot](https://wiki.dovecot.org/MailboxFormat) are supported in iRedMail.
!!! attention
@ -19,6 +20,19 @@ Dovecot](https://wiki2.dovecot.org/MailboxFormat) are supported in iRedMail.
Check its [API document](./iredadmin-pro.restful.api.html) (expand all
parameters and search `mailboxformat` or `mailboxFormat`).
!!! warning
With `mdbox` format, if mailbox index files are damaged or lost, mail
messages will be lost. Because one of the main reasons for dbox's high
performance is that it uses Dovecot's index files as the only storage for
message flags and keywords, so the indexes don't have to be "synchronized".
Dovecot trusts that they're always up-to-date (unless it sees that
something is clearly broken).
Please read documents on Dovecot website to make sure you fully understand
the pros and (most importantly) cons of the format you're going to use:
[Mailbox Formats](https://wiki.dovecot.org/MailboxFormat).
!!! warning
- Changing mailbox format does not migrate existing mailbox for you. You

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html/change.mailbox.format.html
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@ -16,14 +16,15 @@
<span>iRedMail</span>
</a>
&nbsp;&nbsp;//&nbsp;&nbsp;<a href="./index.html">Document Index</a></div><h1 id="change-per-user-mailbox-format-eg-maildir-mdbox">Change per-user mailbox format (e.g. maildir, mdbox)</h1>
<p>iRedMail uses <code>maildir</code> mailbox format by default, it's easy to migrate and
maintain, but if mailbox size is growing, the performance will be getting
slower due to too much disk I/O. Dovecot's own mailbox format <code>mdbox</code> has very
good performance for large mailbox due to reduced disk I/O.</p>
<p>iRedMail uses <code>maildir</code> mailbox format by default, it's easy to backup, migrate
and recover. As long as mailbox grows larger and larger, the performance will
be slower due to too much disk I/O - caused by <code>maildir</code> format. Dovecot's own
mailbox format <code>mdbox</code> has very good performance for large mailbox due to
reduced disk I/O.</p>
<p>You may want to switch to other mailbox format for some reason. To help you
switch easily, iRedMail-0.9.9 introduces 2 new SQL columns (for SQL backends)
and LDAP attributes (for LDAP backends) to help you switch per-user mailbox
format easily. All <a href="https://wiki2.dovecot.org/MailboxFormat">mailbox formats supported by
format easily. All <a href="https://wiki.dovecot.org/MailboxFormat">mailbox formats supported by
Dovecot</a> are supported in iRedMail.</p>
<div class="admonition attention">
<p class="admonition-title">Attention</p>
@ -37,6 +38,18 @@ Dovecot</a> are supported in iRedMail.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>With <code>mdbox</code> format, if mailbox index files are damaged or lost, mail
messages will be lost. Because one of the main reasons for dbox's high
performance is that it uses Dovecot's index files as the only storage for
message flags and keywords, so the indexes don't have to be "synchronized".
Dovecot trusts that they're always up-to-date (unless it sees that
something is clearly broken).</p>
<p>Please read documents on Dovecot website to make sure you fully understand
the pros and (most importantly) cons of the format you're going to use:
<a href="https://wiki.dovecot.org/MailboxFormat">Mailbox Formats</a>.</p>
</div>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<ul>
<li>Changing mailbox format does not migrate existing mailbox for you. You
have to migrate it <strong>BEFORE</strong> switching to new mailbox format, then