>we are planing to build a free mailsite for 200K+ Users. I'm a little
>concerned about the scalability of imail, we are also evaluating sendmail on
>Linux (although I don't favour a Unix solution) also mailsite from Rockliffe
>and sendmail for NT. I have a couple of questions that I'd be thankful to
>get an answer for from people like you who are already using imail
>
>1. is anyone runing that high number of users or know of anybody runing such
>a high volume on imail?
We have reports of one user wtih 250k on one box. There are many in
the 100 to 200K range.
>2. what is the maximum server number that imail peering support?
I personally don't think Imail peering is scaleable (in fact, I see
it as anti-scaleable), and if you're running web messaging, that
function is not "peered". web msging users still have to know which
Imail server their mailbox is on.
>4. we tested scale up and scale out with one 8way Xeon 550 MHz, 4GB RAM, 512
>GB RAID 5 vs. 4 dual Pentium 3 800MHz, 1GB RAM, 100 GB RAID 5. what's your
>opinion?
don't use one box for everything.
Use IMGate as a front-end relay-only mail hub to off-load
sending/receiving mail, anti-spam, various defenses. your imail box
just does pop3/smtp auth/web messaging.
For storage, separate your mail queue + logging storage from your
mailbox storage, using separate controllers+disks for each. RAID5 is
not the best for mail systems.
Look at RAID 0 + 1 : http://www.acnc.com/04_01_0p1.html
>8. is it possible to run the imail webinterface on separate servers (boxes)
>for loadbalancing?
no, and this is the critical issue that limits the scaleability of
the web messaging. Your box is huge overkill for smtp/pop3 for 200+
accounts, but if you're planning to be 100% web messaging service,
assuming 10% of your clients doing web messaging simultaneously,
that's 20K on-line web users.
>9. what are the best load balancing scenarios known for imail?
IMGate will "load share" the burden for one or more Imail
boxes. You'll need two IMGate boxes for MX redundancy.
If you plan serious list server volumes, you'll need a separate list
server. I've recently up an send-only list server doing 40K messages/hour.
You better talk to Ipswitch for their experience with "load
balancing" or some users in this list who have done it.
There is one guy from Zuid Afrika in this list with 750K Imail users,
but he uses 18 Imail servers to to do it.
>10. should the DNS server run on a separate Box? etc....
yes, no question about that, and you'll need two DNS servers for redundancy.
Len
http://BIND8NT.MEIway.com : Binary for ISC BIND 8.2.3 T9B for NT4 & W2K
http://IMGate.MEIway.com : Build free, hi-perf, anti-spam mail gateways
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