Collecting Emails over the Phone- Still CANSPAM? HELP

Okay guys,

So if im obtaining email address over the phone from customers who purchase thru us, and we want to email them.

How does this work with email campaigns? I know some email services like Constant Contact, iContact require you to have an IP address so they know the list isnt purchased or anytihng, but what if im not collecting the emails online but over the phone?

Does that still qualify as Opt-In and am i able to LEGALLY email them products and updates about their order statuses etc

Thanks guys!

For companies like aweber with double opt in it won't work. For icontact or mailchimp it can work for small lists where proof isn't compulsory.