If some ponsy Lord gives you a mission to give a letter to another Lord, the fool won't be at the place you're initially told he is. Unlike RPGs, where you get a mission and it's all linear and some NPC is statically waiting outside a cave for you to deliver him his magical golden grapes, the Lords in M&B are always off impaling peasants on some selfish crusade.
What you have to do when you accept one of the "Give my old pal Lord Wetpants this letter please chap. He's in Swinedale." missions, or any mission which involved locating someone, is ride to a castle affiliated with that lord and talk to the lord there and ask him where Lord Wetpants actually is. The fool is bound to have gone off to do some slaughtering since you got the quest, so won't be where you're told. Normally then you can track him down, and bestow upon him the useless letter, and get your 3 denars of payment.
I too wondered around a town aimlessly before, until I learnt about that. The thing is, it's so obvious. Why would anyone stay in one place all the time, and be there 3 days after you got the quest? The only reason why we expect them to be there is because of the inadequacies of other RPG games, where NPCs are pointless stooges.
Anyway, rant over!
Mount & Blade ftw!
