I feel this way with respect to sites that I am forced to sign up for just to view the demo. Sites that I will never use again ... I don't want them being my best friend yet.

If I've tried the demo and I am actually signing up to use your site, this type of email would be tolerable, but again, I generally don't want to engage with the company unless I have an issue.

The only time I can see this being welcome to me is in a B2B context where I have signed a longer-term contract for a solution that my business will need support for.