What do you think about using an online bank for my emergency fund?
It's not a bad idea at all, as long as you can easily check out the institution's reputation and stability. There are lots of financial scams online, so you want to do some research and make sure they're a reputable and trustworthy organization.
Due diligence is the key, Raphael. There are reliable household names that are online banks, but you can't just assume the group you're dealing with online is made up of honest, stand-up folks any more than you can with a traditional brick-and-mortar bank. Make sure you take your time and know exactly what you're getting into before going into business with them.
Remember, it's not as simple with an online bank as just walking in the door to get your money back if something goes wrong!