all-whitespace autoresponse not sent by Google

[simon-weber]

I noticed a spike in responses, which turned out to be from a user with an autoresponse set to all spaces (my guess is that they wanted to disable it and didn't notice the delete button).

I just tested this, and it turns out to not send anything to the other end, even though we don't get an error. This should be enforced in the form (maybe with a tip to delete it instead) and maybe the db too.