Hushmail has a free plan that includes 25mb of storage. It's important to note, that in order to keep it active it requires signing in at least once every 3 weeks. Subscription versions increase storage capacity and remove the mandatory sign-in.
We offer a free account with limited storage (25 MB) and no mobile or desktop access. [..]You'll need to sign in at least once every three weeks to keep your free account active.