Unlock by email feature

[rarguelloF]

I wonder if you would be open to implement this feature in the lock module, similar to what devise does.

Please confirm me and I could work on a PR, adding a configurable option for unlock strategy and making it optional.

Thanks in advance!

[aarondl]

Absolutely. I'll work with you to code review it etc. If you need any help/advice just add comments to this issue.

One thing to note is no new modules should be using the side effect import method.