Number of copies of messages?

Rob Siemborski rjs3 at
Wed Jun 11 13:35:51 EDT 2003

On Wed, 11 Jun 2003, Bob Jones wrote:

> Hello all.  I've been tasked with looking at changing our mail
> services and one of the options is Cyrus.  One question that will
> greatly impact the decision is this:
> How many copies of a message are saved in the message store?  I know
> Cyrus has a db backend, so we're wondering if one message is sent to
> all users on the server, is only one copy of that message saved in the
> store or is there an individual copy of each message for each user saved?

Cyrus only uses databases for the mailbox list and some other indexes.
The messages are saved in a format similar to maildir (message per file,
but theres additional indexing/caching metadata for performance reasons).

One copy of the message is saved per LMTP transaction per IMAP partition,
so if your MTA sends a message to 1000 users in 1000 LMTP transactions,
you'll have 1000 copies.

If it sends it to 1000 users in a single LMTP transaction, but these users
are on two different partitions, you'll have 2 copies of the message.

If they're all on the same partition, you'll have only one copy.

Nothing is done to proactively detect duplicate messages and hard-link
them (for example, if 1000 users APPEND the same message, nothing is
done and you get 1000 copies).


Rob Siemborski * Andrew Systems Group * Cyert Hall 207 * 412-268-7456
Research Systems Programmer * /usr/contributed Gatekeeper

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