Pinterest Twitter friend notification email messages

A while ago, Pinterest removed the need to request an invitation to sign up: you can now go to www.Pinterest.com and register immediately.

It now looks like there are three options for signing up:

Using your Facebook account
Using your Twitter account
Using an email address.

(However I can't confirm that the email address works or not - it didn't the last time I tried.)

Now, if you sign up via Twitter, there'a a question at the end of the registration process about whether you want your Twitter followers to be notified that you've joined Pinterest. I'm pretty sure that this wasn't there the last time I signed up for a Pinterest account using a Twitter account. But I ticked it - expecting that people might get some type of notification inside Pinterest.

However what actually happens is that an email message is sent to the email account of any Twitter followers who are already on Pinterest, telling them that you have just joined and inviting them to "make you welcome" - presumably by following you on Pinterest too.

The message reads

"Hi <<recipient's Twitter account name>>
Your Twitter friend <<your Twitter account name>> just joined Pinterest. Help welcome <<your Pinterest account name>> to the community."

I'm fairly sure that the message is only sent to Twitter followers who are already registered in Pinterest themselves - not all your Twitter followers.

But I was a little surprised by this.

Sending an email is a little more invasive than I'd expected (and maybe shows that Pinterest is looking to do things with the linking data it collected when forcing us to sign up via our existing Twitter or Facebook accounts)####

Really I don't expect my Twitter followers to be following me on Pinterest. I'm looking for a different target audience on Pinterest, not more of the same people who are following me already.

And I'm a little worried that Twitter followers might think I've spammed them by telling them that I've joined Pinterest.