I've had a Poloniex account for quite a while, although I'm not a frequent trader, I've used it enough to understand how it works.
Every time I've logged in there would be an email from Poloniex to the effect 'Successful login from new IP address'.
But that, along with a recent withdrawal request to an address I had not previously used, has triggered Poloniex to pull the rug out from under me. They've gone from nagging me about two factor authentication to insisting upon it even though I previously explained that I don't have the means to use it - I abhor mobile phones.
Rather than pointing out that using a mobile phone isn't strictly necessary to jump through their two factor authentication loops (which I only recently discovered), or give me the opportunity to cancel my 'objectionable' withdrawal and try again with an address I had previously used, or allow me to authenticate myself some other way (such as signing a message with a previously used address), Poloniex is instead forcing me to re-authenticate myself.
As much as I hated to again violate my privacy, I want my money out of their control even more. 12+ hours later, still no withdrawal.