Thanks for all the replies about IMAP. Sorry for the delay in posting
this; we've been busy installing our new system.
Five IMAP servers were mentioned, including two I never heard of before:
Washington University
Cyrus
Innosoft
Digital Internet AlphaServer package - includes IMAP4
Netscape
Replies are attached, slightly edited for length.
- Jerry Berkman, UC Berkeley
jerry_at_uclink.berkeley.edu
(510)642-4804
Original question:
We currently run a mail server on an Alpha 2100, soon to be upgraded to
an Alpha 8200. We have about 35,000 accounts. We currently only allow
POP access, but are looking at allowing IMAP access also.
Is there a clear "best" IMAP server which runs on the Alpha? If not,
what are the advantages and disadvantages of the various IMAP servers?
What resources will we need to support 40,000 users? (memory, disk,
cpu, ...). How much disk do most users use?
We will probably offer both POP and IMAP. Is this reasonable? Can you
switch back and forth easily? If the mail box format is different, is
it reasonable to set up a way for users to switch back and forth? E.g.
there could be a Web interface they need to use to switch before
reading their mail.
==================================================================
Richard Jackson <rjackson_at_gmu.edu>
George Mason University, Fairfax, Virginia
Uses WU IMAP4rev1 on systems for 45,000 users and supports IMAP and POP
See -
http://www.washington.edu/imap or
ftp://ftp.cac.washington.edu/mail.
==================================================================
Julian Rodriguez <Julian.Rodriguez_at_digital.com>
Buy Digital Internet AlphaServer package - includes IMAP4,
plus a bunch of other useful Internet tools.
==================================================================
Tim Winders <twinders_at_SPC.cc.tx.us>
Network Administrator, South Plains College
I use the Washington University POP3/IMAP servers. The imap code is
constantly revised and I download updates frequenty. The biggest gotcha
is with Netscape Mail you have to specify a mail directory on the server.
The format of the mailboxes is the same for THIS imap/pop3 implementation.
With some other imap servers, you have to converst the mailbox between the
two formats.
> What resources will we need to support 40,000 users? (memory,
> disk, cpu, ...). How much disk do most users use?
Wow, that is a lot of users. How many machines are these users spread
across? The deleted messages remain on the server until their imap trash
is emptied. With enclosers you could easily have a user with 10MB mailbox
space.
> We will probably offer both POP and IMAP. Is this reasonable?
> Can you switch back and forth easily? If the mail box format
Again, with the WU stuff it is very easy to switch back and forth. I find
imap very nice if you have multiple machines, but it "feels" slower to the
user because each message is download only when you read it, whereas POP
downloads all the messages when you connect. I think it is just
perception. There is also quite a bit of learning involved with the imap
online/offline concepts.
==================================================================
Dave Tetreault <davet_at_uriacc.uri.edu>
University of Rhode Island
The two big players in the game are Washinton and Cyrus from CMU. The
Washington server uses conventional Unix mail boxes. Cyrus uses it's own
structure and does not allow 'native access'. The word from both
developers is that if it is only a server (No shell users on the box)
then Cyrus is better. They both support pop3. We chose Cyrus and expect
to support 40k users.
==================================================================
Daniel.Clar_at_supelec.fr (Daniel Clar)
There is an Imap server with the Internet Alphaserver System Software,
==================================================================
Ed.Murphy_at_ussurg.com Thu Jan 15 10:20:03 1998
United States Surgical Corporation
Take a good look at Innosofts PMDF product. www.innosoft.com
==================================================================
Stephen LaBelle <labelles_at_mscd.edu>
Metropolitan State College of Denver, Denver, Colorado
I suggest you might want to look at running PMDF on your Alpha.
They have a very good product which ties mailers and messaging together,
we started with them back in the days when we have VAX/VMS machines and
continued with them when we went to APLHA's of Digital Unix.
PMDF is a sendmail replacement.
You can find out about their products at
http://www.innosoft.com
BTW, you can support POP and IMAP on the same machine at the same time.
We do both because we have users whom want both.
==================================================================
Gary Gladney <GLADNEY_at_stsci.edu>
If you are willing to pay some money, about $1000 I think. Netscape mail
server works real well on Alpha running Digital unix. I get downloaded the
trial version.
==================================================================
Nebojsa Hrmic <nebojsa_at_alf.tel.hr>
Admin for tel.hr domain
Hello!
We are having 20,000 accounts on Alpha 1000A, which is serving
them as DNS, mail, POP (qpopper) and authorization server. Only some of
them are telneting to the machine, primarily those using WWW server which
is also on that machine. Now, we are removing some services to new 4100s.
I was also thinking of IMAP, since user may have problems with manipulating
their mail on the server. I have no experience with IMAP at all, but in my
search of this list archives, I notice Washington University server beeing
mentioned.
> How much disk do most users use?
It depends. We are moving to more disk in the maildisk, since most users
are not using home dirs, but mails are getting bigger because of attachments.
==================================================================
Becki Kain <beckers_at_josephus.furph.com>
have you gotten any answers? I am also looking for a secure IMAP, and,
preferably, a free one!
==================================================================
Dirk Grunwald <grunwald_at_foobar.cs.colorado.edu>
Assoc. Prof, Univ. of Colorado at Boulder
I've been told that an advantage of e.g., the Netscape Mail server is
that it stores the mail in a compressed format, reducing disk
bandwidth. It supports both POP and IMAP. I think it's free to
universities.
We use the UWashington imap deamon right now, but don't have a
centeralized imap service.
There's also a question of having an LDAP server for authentication.
We're running the Netscape LDAP server for this purpose (mainly to use
with the Netscape calendar tool).
==================================================================
Arnaud TADDEI <Arnaud.Taddei_at_cern.ch>
CERN
Dear sir, as being project leader for e-mail at CERN, we have maybe some
information relevant for you.
We are running an IMAP/POP service based on multiple hosts which
consists of several platforms.
We have 8000 registered users and we are expanding to 12000 users.
We are running 2 2100 machines with 3 CPUs in it for each of them and
512 MB of memory. The data are on RAID5 connected via HSZ40C or HSZ50 to
each of them.
mail1 is supporting 6000 users and mail2 2000 users. mail1 IS overloaded
and we are going to offload some thousands of users to new machines
(mail3, etc.) which are Solaris platforms.
We export one virtual IMAP server per user such that we can scale. Each
user connects to $user.mailbox.cern.ch. This DNS mapping is used already
by several big universities like the University of Washington which is
supporting 70000 users on 20 IBM AIX low machines.
We allow 10 MB of disk quota on the server for the folders and UoW
allows 5 (but CERN is dealing with real professional researchers ;-)
On the software side, we are using the University of Washington server
from the IMAP author himself. There are few things that you must deal
with which are absolutely strategic like choosing the mailbox driver
format on the backend side of the IMAP server. This will heavily impact
your response time, locking mechanism, quota, file layout, etc.
We are happily running the Public Domain sendmail version.
A good IMAP server seems to definitely be the one of Sun (SIMS) but of
course you would have to run on new hardware, etc.
> We will probably offer both POP and IMAP. Is this reasonable?
Yes, well let's say that in a short future POP users will feel very
uncomfortable
> Can you switch back and forth easily?
Well, we DON'T recommend users to mix POP and IMAP as POP is giong to
spread around files. In particular if users are using different
computers and moving between them (at home, with portables, even withthe
Nokia 9000 mobile telephone), the ONLY way to treat that correctly is to
use IMAP based clients.
> If the mail box format
> is different, is it reasonable to set up a way for users to
> switch back and forth?
On the server side, the mailbox format will be the same. ANY IMAP server
will offer POP service as IMAP is a superset of POP.
> E.g. there could be a Web interface
> they need to use to switch before reading their mail.
Well no! forget about this idea it doesn't work like this.
We started IMAP in 1995 at a period when only pine was able to speak
IMAP correctly, we accumulated some experience here!
==================================================================
Mikel Stous <stous_at_sol.cstp.umkc.edu>
University of Missouri - Kansas City
> Is there a clear "best" IMAP server which runs on the Alpha?
> If not, what are the advantages and disadvantages of the various
> IMAP servers?
It was importaint for me to have a "name brand" so I can use it's name
to advance system migration to IMAP. Also I wanted LDAP support.
The Netscape server is free for the Academic side of the University.
> What resources will we need to support 40,000 users? (memory,
> disk, cpu, ...). How much disk do most users use?
We all know that whatever we buy isn't enough.....for 400 like me
or 40,000 like you....dang I can't even count that high.
I wish that I had a standalone machine with no user logins on it.
Thoughts on your situation:
Use a mail routing machine to drop mail onto distributed servers. In the
Netscape LDAP user manager you can specify the server that can accept
email for that entry. Or you could cluster the machines and RR DNS
(or vary by load) reference them.
I think easy server name resolution would be important. Something like
stous_at_s.imap.umkc.edu could resolve to a server in a grouping of machines,
or just straight stous_at_imap.umkc.edu would be simple enough.
> We will probably offer both POP and IMAP. Is this reasonable?
> Can you switch back and forth easily? If the mail box format
> is different, is it reasonable to set up a way for users to
> switch back and forth? E.g. there could be a Web interface
> they need to use to switch before reading their mail.
Offering both is easy. Regular POP clients will only be able to download
new mail off of the server. IMAP clients can either download new
or store locally or keep mail in folders on the server.
Moving from POP to IMAP will be simple for some of the faculty here.
We use Eudora Pro and IF they can upgrade to the newest version then
I can drag their POP'ed email onto the server. The Mac version won't
be out for another few months.
Point is, if they need the capabilites of IMAP then they don't need
to go to POP except in special circumstances. (ie personal email
off of their ISP. But even then they can use an IMAP client to do that)
==================================================================
"Todd B. Acheson" <acheson_at_ohiou.edu>
I support from 35,000 to 50,000 accounts.
Currently my server is a 4100 with 3 cpus, 1 Gigabyte of RAM and 120
Gigs of RAID 5 across two controllers.
We are in the process of migrating from IMAP2bis with pop as a proxy to
IMAP to IMAP4.
There appear to be two primary IMAP4 servers 1) Carnegie Mellon's Cyrus
and 2) U of Wash.
The Cyrus server appears to be the more robust and more widely used.
It is a "black box" only server so there is no availability of the
message stores (folders) through the UNIX environment. You must
manipulate and access the messages only through the IMAP interface.
The U of Wash server I believe allows you to access messages stores
from UNIX (Berkely format folders) if you wish.
I am using a variant of the Cyrus server produced by Esys Corp. Esys
has what is probably the best IMAP products www.esys.ca
One thing that is very nasty is the conversion process from Berkely
Mail to IMAP. It can be done with scripts but is slow.
I am in the process of testing my conversion tools. I currently have
420,000 messages in INBOXes in /var/spool/mail. I estimate it will
take a minimum of 8 hours to convert these to IMAP 4. This doesn't
include the other folders I must convert. If you are converting from a
POP only environment then your life will be relatively easy.
The Cyrus IMAP4 will require sendmail 8.8.x
POP is a proxy to IMAP in any environemnt.
Received on Fri Feb 06 1998 - 19:32:41 NZDT