Bulletin Boards can be found in each overland zone near high traffic areas and outposts. The residents of these zones have requested help from Drifters to deal with their troubles in the form of Bulletins. These are bite-sized adventures that whet your appetite for larger excursions. Clicking on a sealed envelope will accept a randomized Bulletin which provides a brief note from a local detailing the request, the appropriate level range, and the objective to complete. A single Bulletin may be active for each zone and you will be unable to obtain another until it is completed.
Bulletins are tracked within your log on the "Bulletins" tab. While all Bulletins are designed to be completable by a solo player, objectives can also be completed with group content within the same zone, or nearby Ember Veins. Once completed, the Bulletin can be handed back in at any Bulletin Board within that zone for some experience and the "Warm Welcome" buff (which provides a bonus to health regen) in thanks for their service to Newhaven.
There is no limit to how many you can turn in which allows you to do them at your own pace. Each Bulletin is drawn randomly from a pool and must be completed before you can acquire another within a specific zone (they cannot be dropped). The experience rewarded for each turn in is proportional to the Bulletin's level range; in order to maximize the benefit from turning in a Bulletin try to do so while you are within its level range.