Is there an Interweb expert in the house?

I got most of the way through ordering a RoadID but then changed my mind and bailed out. The next day an email from them arrived, saying I didn't complete my order and could they help. But I don't recall giving them my email address because I didn't get to paying. I don't give out that particular address unless I mean to.

I wrote back asking how they had obtained my address. I've not had a reply.

Apparently RoadID are a reputable company. And maybe the email from them was automated and from a don't-reply account.

If there's anyone on the forum who understands how the back end of a website works - is it possible to harvest my email without me giving it? Or must I have given it but forgotten?

I'm not alleging anything sinister or improper, just curious more than anything else.