hopefully the next firmware update will do some good in this area.
But i have to say that i am not really optimistic

It seems that writing a good IMAP email client is very difficult.
The N900 is as in internet device good in Web and IM but Email is really lagging behind and that are the 3 things you do the most on an internet device.

If only the gmail mobile app (written in java) would work on the N900 that i used on the E90. then at least gmail would be usable, but also that is something that i lost when moving to the N900

Hopefully the IMap client will be improved in the coming times, like imap idle, sent box support, much better (configurable) ui, fully configure stuff like download X number of emails, download X number of headers per folder. Monitor only folders A and B, Searching (online imap search or offline)

And if we take it to the next level, integrate email more into contacts just like IM and SMS....