Hello! I'm insomniac and having a horripilant and monstruous Internet! Ssssso let's make a newbie guide.
If you are new to the game or have been at some point, I am sure you remember a very common issue - not being able to find an specific person.
Most people find this problem when they are looking for a mentor or a guild member, but that needn't to be the only case. Perhaps you are also looking for a miner to get some ores for you or a bookbinder to get blank books. Perhaps you are a high commander and heard of the breathtaking skills of that sexy beheader. Perhaps you have fallen in love at first sight and want to confess your feelings. Perhaps you are in a romance roleplay and you've discovered your fiancée's amant. Perhaps it's all at the same time. The key is the same.
A 'mailnick' (or a 'folder name' as I like to call it) is a special nick you submit in a Post Office. These you can find them at any city or village - the initial map displays where they are. But a 'mailnick' function is simple: it allows you to be contacted by characters you don't know of.
Having a set up mailnick is very important, since odds are you will meet some people this way. Being GEAS a game played by people of different backgrounds and zones, it is hard to stumble into each other. Characters such as important as guild representatives or those seeking to trade highly benefit from features like this. Making your mailnick the same as your characters' name or leaving it at a post office is also very helpful for intuitive reasons.
If you want to know more, as on how to submit this nick exactly, get into the game and type 'help mailnick'. This is just a very simple explanation post to highlight the feature.