Nokia Messaging for Email is apparently getting an update thats being rolled out in the coming weeks.

The update brings along a couple fixes, the most significant of which, is related to Destinations support on Symbian^1 devices (like the Nokia 5800 and N97).
From the Messaging Blog :
Several issues were resolved around reliable WLAN connectivity. Please note that there are two steps to successfully enabling WLAN roaming: add your WLAN access points to the Internet Destination, and then also enable WiFi “sniffing” so that the device will notice when it comes into range of a configured WLAN. This “sniffing” setting is found under Settings / Connectivity / WLAN / Settings / Scan for networks. You can then select your Destination profile inside of the Nokia Messaging client.
You can eventually get the update when it’s available, through the Ovi Store and at their Service website, as well as through the Software Update app on your Symbian^1 device. Or if you just cant wait, grab the installation file from the Messaging Blog post.
Gotta love the Messaging Team for finally fixing this eh?