Can I send bitcoin from my wallet using a client with a grossly outdated blockchain? If not, is there a way to load my wallet into some app or service that doesn't require a local copy of the entire blockchain? Sorry if this is a stupid question. I've been researching, but nothing seems to address my situation. Thanks in advance.
Possibly not, unless you haven't touch it since the block that the client is synchronized to. The transactions would not appear till your blockchain gets synchronized to the block the TX is included in and not having it synchronized completely would risk your client spending a input that has been spent before and thus confuses the client. It would not be propagated either. If you really want, you can script a unsigned raw TX at coinb.in/#newTransaction and sign it using the console in your Bitcoin Core client. Electrum, Multibit are great alternatives as SPV clients but if you want to use the address repeatedly, you need to keep a local backup of the private key. If not, the seed will not recover the imported key.
