The "delete from..." is not available on the N900 (at least not for imap). Why not use the webmail client?!?! This is more a corporate style client. Yes you can access your email, but it's not ment for this. really slow. Besides I would have to log on and check my mails. I have my email on the N900 set as to check constantly (when connected), so I get my mails right away. Having to log on every 15-30 minutes would be a lot of work and wasted time.
I know I should not do this, but I am trying to use the N900 for my work. And yes, though the N900 is the new flagship, I guess I am regretfully experiencing the difference in between the N and E series. N=flashy and impressive even for iPhone users ,-). E=reliable workhorse for professionals. Man, I used to work for Nokia like about 10 years ago, I knew about the stuff before it hit the market and there have been so many nice cutting edge developments that were actually working to at least 75% on release of a new phone...Guess those days are over.....