On Sun, 29 Jul 2012 20:21:53 +0500
Muhammad Yousuf Khan <email@example.com> wrote:
> ok our 20 users fetching their emails from our hosted server. which is
> maintained by our service provider. and we are keeping 3 months of
> emails on our mail server and in case of email lost we can not recover
> it since we have no backup. so my proposal to my management is if we
> place a centralized mail server we can make backup of users email from
> our mail server and old mail can also be restored. you can call it
> migrating or shifting
. but the purpose of the whole idea is to
> backup all emails and to provide more options to the users like web
> access and our users will be independent from our service provider
> and will be coordinating directly with me in any problem..
Under normal circumstances, the receiving MTA deposits email in files
or folders in the user's home directory on the server, as plain text.
The user would normally access this mail by webmail, POP or IMAP,
though he can open the emails with a text editor from within the home
This makes it difficult to lose many emails at one time, a single email
corrupted by a bad file transfer will not affect any others. If you use
an SQL server to store emails, as Microsoft Exchange does, there is the
possibility of a large number of emails being lost in the case of a
file corruption. If, in addition, you encrypt the database for
security, you can pretty much throw it away if it gets corrupted, there
will be little chance of recovery of any of it. You gain a lot in
security and centralised backup, but problems can be much more serious.
If you decide to go with simple text email storage in IMAP folders
mapped to real directories, you can configure the MTA to deliver
everyones' emails to individual folders but in a central location
instead of their home directories, for ease of single backup.
> >> therefore i presented the idea to management for IMAP.
> > Well, yes, IMAP is good for migrating messages but can be slow if
> > there are thousand messages to move or copy and/or if the IMAP
> > server is accessed over Internet (I mean, not "locally").
> >> so i think my basic need are. POP emails from hosted server.
> > If you mean to fecth POP e-mails from your server to place them in
> > your own server, Fetchmail or Getmail can do the jobs as I already
> > told you.
> > Once the messages are in your server, they can be accessed locally
> > via POP, IMAP or directly put into the user's home.
> >> IMAP for local users,
> > Good.
> >> ldap for AddressBook/contents update.
> > OpenLDAP can hold this but it can take you some time to configure
> > it. For a bunch of users maybe you should reconsider it.
At the moment, email clients seem only to be able to access remote
email directories using LDAP. If you want a central, shared address
book, LDAP appears to be the only option. I run OpenLDAP on my server
solely to provide about forty email addresses to a mixture of clients
and operating systems on three or four machines. I'd quite like to use
an SQL server, which I do use for many other things, but email clients
haven't quite got around to dealing with SQL servers yet. I've yet to
see one capable of actually saving new contacts to an LDAP server, I
have a web application to add new entries, which cannot be integrated
with any email client. But it's the only game in town...
Every now and then, I look around to see if there is a simple LDAP-SQL
gateway (LDAP queries for address books are fairly simple, and map
easily to SQL) but I haven't found one yet, and I don't have the time
to write one.
> >> spam filter and antivirus scan.
> > Antispam is necessary, the AV only when supporting windows clients.
> >> and obviously Web access for clients.
> > Then you have to add a web server and a webmail service :-)
Difficult to imagine a server that does not do web serving.
> >> and i dont know if SQL database is better then local mail folders.
> >> because mdeamon use to store data in a folder. but i think SQL is
> >> much more better then that.
Better in some ways, worse in others. Google for exchange mailbox
recovery. Of course, you don't have to make the same mistakes as
> > A SQL datadase for storing 20 users is a bit overwhelming, IMO. It
> > will require an extra component (MySQL, PostgresSQL or SQLite) and
> > the benefit of having a database for that small amount of users can
> > be unnoticed.
If you need that level of security, search and backup convenience, you
need it, no matter how many users. A lot of professions in the USA are
required to use a specified level of security in their IT systems, so
it is only a matter of time before an EU directive forbids the use of
plain text files to store email...
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