1MAILDIRQUOTA(7) Double Precision, Inc. MAILDIRQUOTA(7)
2
6 maildirquota - voluntary Maildir quotas
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9 maildirmake {-q} {10000000S} {./Maildir}
10
12 maildrop has an experimental quota enforcement implementation. This is
13 an option that is set at configuration time, and may be disabled.
14 Filesystem-based quotas should be used whenever possible. However
16 filesystem-based quotas cannot be used in some situations, such as
17 virtual mailboxes. If this experimental feature is enabled, approximate
18 quota enforcement can be implemented by maildrop or deliverquota to
19 whatever extent it's possible to do so. Quotas are enabled by the -q
20 option to maildirmake. Both maildrop and deliverquota will observe any
21 maildirmake-requested quota.
22 LIMITATIONS
24 This quota mechanism will only work as long as maildrop (or
25 deliverquota) are the only applications that deliver messages to the
26 maildir, or as long as other applications implement the same quota
27 enforcement mechanism. The quota enforcement mechanism is described
28 separately in the README.maildirquota.html file in the source code
29 distribution.
30 Quota enforcement will still work, to some extent, if there are other
32 applications that deliver or modify messages in the maildir. However,
33 quota enforcement may not kick in immediately when the maildir goes
34 over quota, in fact the maildir can go over quota by a noticeable
35 amount. But eventually, as long as maildrop or deliverquota are
36 responsible for delivering the majority of messages, quota enforcement
37 will kick in. Also, other sources of messages may also result in
38 noticeable performance degradation, because quote recalculation will
39 become noticeably more expensive.
40 Also keep in mind that this quota mechanism is generally useless if
42 mail recipients have direct access to their maildirs.
43 Finally even under the best conditions this quota enforcement does have
45 a small chance of a race condition where a maildir will go over quota
46 by some amount. maildirs are designed for speed, and this quota
47 implementation was designed to have as little additional overhead as
48 possible, compared to regular maildirs. To enforce an exact quota you
49 would have to use some kind of a locking facility, which will impose a
50 drastic performance degradation on the overall maildir performance. A
51 decision has been made to avoid locking, with the only negative side
52 effect being a possibility of going over quota in very low probability
53 situations.
54 A way to minimize the risk of going over quota is to set reasonable
56 quotas, in relation to maximum message sizes supported by your mail
57 server. If you set your maildir quota to five megabytes, for example,
58 it makes very little sense to configure your mail server to accept
59 messages up to three megabytes long. Your maildir quota should be
60 chosen so that it makes sense when compared to the maximum message size
61 allowed by your mail server.
62 FOLDERS
64 This quota implementation is compatible with a popular extension to
65 maildir which defines individual mail folders within a single maildir.
66 However, in order to create a compatible folder, you MUST use the
67 maildirmake command that comes with maildrop, and you MUST use the -f
68 option to maildirmake, giving the name of the folder. Do not use
69 maildirmake and specify the directory name of the maildir folder. Quota
70 enforcement will not work if you do that.
71
73 maildrop(1)[1], maildirmake(1)[2], maildropfilter(5)[3],
74 deliverquota(8)[4].
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77 1. maildrop(1)
78 maildrop.html
79 2. maildirmake(1)
81 maildirmake.html
82 3. maildropfilter(5)
84 maildropfilter.html
85 4. deliverquota(8)
87 deliverquota.html
88Double Precision, Inc. 04/22/2007 MAILDIRQUOTA(7)