Some emails not sync

Some users complains sometimes for receivieng emails in zimbra that are not sync in their mobile device (iphone, ipod touch or nokia E series).

I now experienced today the same behaviour. I can list 9 emails that arrived today in my inbox that i can't find in my ipod touch (OS 3.0).

Did you already notice this ? How to fix it ?

Very stange :

just few minutes after posting that subject, the missing emails now appear on my mobile device !!!

I'm sure that sync occurs many times this morning, and some emails that arrived after the 9 that were missing were already sync on my mobile device.