I'm considering zimbra to migrate a 15 users small business server 2003 / exchange.

We're using rim/blackberry bes express as well, with 10 blackberries, which I'd like to replace with android od iPhone phones.
A blackberry/bes feature that we depend on is the capability to read large email attachment without downloading them (bes sends to blackberry only the page it requests): is there a similar function in zimbra or in any addon/ that makes it happen with android or iphone clients as well (preferably using the phone's native mail app)?

Thank you