Hi Mark & All,
We use IMAP and we have not seen the degree of problems that you suggest
with IMail performance though our user count is currently increasing so we
have not reached the same amount of users that you have. We have done lots
of load testing using some custom scripts to hammer the IMAP server
mercilessly and basically couldn't generate enough load to bring it down.
However I would not like to seem complacent so I'd be interested in the sort
of load that you are experiencing i.e. concurrency of the sessions and the
distribution of user types (heavy lan users / lease line connections / slow
connection dialup users).
In our experience we know that handling quick connections is rarely a
problem, it is handling slow, long running connections which is the killer
especially in mail systems where locks have to be used and the possibilities
of time-outs exist. In these situations web messaging is the saviour as the
interaction with the mail storage engine is quick and internal whereas the
interaction with the customer is just html so can be long and none locking.
What I am getting at is that you may experience similiar problems with other
software if the cause of the problem is more to do with the way your users
use the system than the actual system itself.
If I was redesigning the DLL I think I would have the option to do more
caching, i.e. hold recently use usernames and passwords for a short period
in the dll process and when user changes are made then expire the cached
info. If Mike Nice feels like doing more work on the dll (it has been very
appreciated so far) I think that we could all come up with methods of
caching the information and giving better performance. Obviously if Ipswitch
decided to take their own component in hand that would be the better
solution ;-)
Just my .02p worth...
Steve
Steven Moore
Internet Development Engineer
Research Machines
+44 1235 823522
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