[sonnyz]

Ugh, I had to do this once on the sign up page at a small company I worked for about 10 years ago. Ever since then, I've been weary about beginning to fill out any forms unless I really, really want them to have the info. I still think its messed up to store user data that hasn't been submitted.

[Nagyman]

Yeah, there are shady techniques from companies offering cart abandonment solutions that do exactly that (e.g. VEInteractive). If you type in an email address and don't submit the form, they'll still send you chaser emails.

I think there are valid reasons to store incomplete form data, but I don't think it should be used for reasons the customer did not intend (e.g. receiving emails).