[Dovecot] Shared Mailboxes, Per User SEEN flag and Mailing lists

[Reikan - Sidney Ferreira]

	Well, I carefully readed all this mail and also readed about the Hard 
and Soft linking methods.
	This is exactly what I was looking for, so, I'll have Dovecot in my 
project.
	Im just wondering about SMTP, does Exim is a good choice? Will the SMTP 
change anything about the shared box system?

Peter Fern wrote:
> Are you familiar with symlinking/hardlinking under unix?  If not, it's 
> fairly straight forward, and yes - they are like file aliases.  I 
> suggest you google for it to see how it works, or 'man ln'.  You'll need 
> to understand this to make the solution below work.
> 
> For your scenario, linking individual files into user's mailboxes 
> probably isn't the best method - better to use the inbuilt shared folder 
> support in dovecot.  There are two methods of provisioning shared 
> mailboxes in dovecot - using the namespace configuration directives, or 
> symlinking the folders in.  The namespace method will make shared 
> folders available to *all* mail users, so if you want opt-in/-out you'll 
> need to use the symlink method, so for your setup, this would be the 
> easiest method.
> 
> A quick outline on how to make this happen:
> 
> 1.  Create a central store somewhere containing your folders to be shared.
> eg:
> /var/mail/public/.MySQL
> /var/mail/public/.PostgreSQL
> etc...
> 2.  In each of these folders create a file called 'dovecot-shared' and 
> set file permissions to 0644 and set the group to one that your mail 
> users will be members of - this will determine the permissions of mails 
> within the folder.
> 3.  When a user signs up to the folder, create a symlink to the relevant 
> folder under the user's maildir.
> 
> Then just drop mails into these maildirs.  This is all a little 
> off-the-cuff, so if anyone disagrees yell out.
> 
> Cheers,
> Pete
> 
> Reikan - Sidney Ferreira wrote:
> 
>>     Well, here's an example of what I have in mind:
>>
>>     Suppose a programmers server, each one has Inbox, Outbox, etc. 
>> Now, we also have the following shared boxes: C/C++, PHP/Perl, 
>> HTML/CSS, MySQL, PostGreSQL.
>>     Each user may signup for one or more of this shared boxes, being 
>> able to mark what they read and what they didn't read.
>>     The reason, as I said, is to sabe space. Imagine 12000 users, 5 
>> mailboxes, 2 messages a day, it would be 117MB a day!
>>     If I understood properly (what I don't think I did), this hardlink 
>> would be like the file aliases, so, I woul have 1 original message of 
>> 1KB and 12000 aliases to this message, wich wouldn't use much space.
>>     The main point is that I want make it all web based, so, no 
>> downloading-and-deleting work, but, syncronizing.
>>
>>     I hope this help you to help me ^^
>>
>> Peter Fern wrote:
>>
>>> If all you need is to deliver a single mail to many users at once, 
>>> you might consider hardlinking the message into the mailbox - you may 
>>> lose a little space (never more than one block) as the filename entry 
>>> in the filesystem will require nominal space, but it's likely to be 
>>> quite efficient.  Symlinking won't use any additional filespace for 
>>> each link, but will use inodes... I'm not sure whether dovecot will 
>>> handle a symlink for an actual mail message though - I would assume 
>>> not.  In any case, this will only work properly if you are using 
>>> maildirs, but then if you're not, why not? ;)
>>>
>>> Alternatively, the 1.0 series of dovecot does support shared folders, 
>>> and I believe per-user flags are supported, though I'd like someone 
>>> to confirm?  Again, this will only work easily on maildirs due to 
>>> filesystem permissions and such...
>>>
>>> Reikan - Sidney Ferreira wrote:
>>>
>>>>     Hi!
>>>>     Im making a small research about IMAP servers and it's features. 
>>>> As the subject suggests, I want make a shared mailbox, with per user 
>>>> \seen flag to work like a mailin-list works.
>>>>     The reason to use 1 shared folder is simple: Imagine 12k users 
>>>> sending 1KB messages each week, it will be 12+ MB of useless 
>>>> information.
>>>>     Many people told me that IMAP could do this, but now seem that 
>>>> it is a little harder then what they made it look like.
>>>>     Finally, some EXIM users told me that Dovecot could handle it a 
>>>> little better than Courier, so, Im here to try to find more 
>>>> information about it.
>>>>     Follows the mail that I received from an EXIM user.
>>>>
>>>>         Sidney
>>>>
>>>> Bill Hacker wrote:
>>>> > Reikan - Sidney Ferreira wrote:
>>>> >
>>>> >>     Does Exim works as IMAP?
>>>> >>     Does it allow public folders?
>>>> >>     The SEEN control is made by USER or MESSAGE?
>>>> >>
>>>> >>
>>>> >
>>>> > Exim is an MTA, not an IMAP (or POP) server.
>>>> >
>>>> > It works well with most, perhaps all, POP and IMAP servers.
>>>> >
>>>> > Two widely-used IMAP partners are courier-IMAP and Dovecot.
>>>> > Both of these support POP as well as IMAP.
>>>> > There are several others known to work.
>>>> >
>>>> > Folder sharing can be complex.  IMAP is more appropriate than POP, 
>>>> even
>>>> > if other users are on POP.
>>>> >
>>>> > Exim can use Maildir MBox, and other storage types, can use 
>>>> several at
>>>> > once, can select  the storage location, storage type, UID, GID, and
>>>> > privilege mask from hard-coded, flat-file, db or RDBMS lookup, and 
>>>> can
>>>> > create the storage if it does not already exist.
>>>> >
>>>> > All/any of the above can be done on a per-user, per-domain or 
>>>> per-sender
>>>> > basis, and/or on combinations of the above.
>>>> >
>>>> > The rest is up to the IMAP and client configuration(s).
>>>> >
>>>> > Dovecot can handle Maildir, MBox and other.  Courier-IMAP is 
>>>> optimized
>>>> > for Maildirs.
>>>> >
>>>> > Message state assignments are the responsibility of the retrieval 
>>>> agent
>>>> > (IMAP/POP + MUA).
>>>> > The MTA is not involved once the message has been delivered to 
>>>> storage
>>>> > 9or distant server).
>>>> >
>>>> > As an MTA may process multiple valid messages per valid 
>>>> connection, not
>>>> > all for the same valid user, or even same destination server, Exim 
>>>> does
>>>> > routing and delivery in an area that is essentially per-user OR
>>>> > per-destination sensitive, but always per-message relevant, i.e. -
>>>> > normally handled one at a time at the 'decision making' points.
>>>> >
>>>> > HTH,
>>>> >
>>>> > Bill Hacker
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