> But generaly I like to setup such thing like at my german ISP
> <http://www.freenet.de/> which has ONLY <mx.freenet.de> and this
> is where $USER send (SMTP) and get (IMAP/POP3) there E-Mails but
> teh mailboxes are physicalay <mboxXX.freenet.de>
My setup is pretty easy really. I map each mailbox to a specific mbox
server, forwarding mails to it, and proxying POP/IMAP there. The approach
is popular enough that a number German providers works that way. As can
be seen from headers, the third important block is mout.freenet.de to
hold the queue of outgoing mails.
If you want to save a little latency, I guess you could build such a
setup for each country, but I doubt it is worth it. My parents use cell
phones with local providers and satellite phone otherwise for accessing
their mail from all around the world and latency is not their major
problem, but bandwidth of their local connection is (for mail, web is
a different issue).
> It seems that each <mboxXX.freenet.de> can hold around 60.000
> Accounts because Freenet has around 4,5 million E-Mails and 80
> Mailbox-Servers.
About, because there are different mbox servers with different storage
capacities. But you got the dimensions right. A distributed approach
means being able to use storage hardware as long as you can keep
it working. You save on hardware, but pay on administering a more
complicated setup.
All you need is a router that gets active on mailbox addresses and a
transport that uses "gethostbyname", "max_rcpt = 1" and "hosts" set to
the storage server for the address, obtained by a lookup on the address,
as well as a POP/IMAP proxy server. In theory, because the devil is in
the details, and there are lots of them.
Michael
