[Dovecot] Slight problem with dovecot + IMAP

[Timothy Murphy]

I'm running dovecot on my desktop
with kmail as IMAP client on my laptop.

When I start kmail on the laptop
it sometimes takes several minutes to "calm down".
The number of messages listed in the IMAP inbox increases greatly -
maybe from 2500 to 3000 - and then slowly decreases.
There are sometimes a large number of duplicate messages,
which kmail allows one to delete.

I don't know if this is a kmail or dovecot problem.
It is quite likely there is something wrong in my setup.

Any suggestions or advice gratefully received.