well you see ryuuga, not everyone can send mail....that's a VIP and higher perk. /seen may not tell you when they're coming back online, but it can tell you how long it's been so you can msg them through de forums or other communications. /seen should just be a command that could be used by all except for builders. This would encourage builders to become members then possibly VIP.

In short, make /seen a member and higher perk.