MMs and Specialists do not post bids/offers after hours. Specialists clear the building at 4. Market makers, in the case of NASDAQ stocks, will use an ECN to execute orders.
Everyone can use them, but most of the software we all use through our online accounts has automatic routing in it that is designed to get the price price. You could probably turn that feature off or manualy direct how you want your order placed. So if you saw that 3.23 bid after hours, you could (or should) be able to hit that bid.
News 
Market Data 
Discover 
