You need to make it easy to unsubscribe from your email list. Here's why:

1. The bigger your list, the more it costs. Only send to people who want it.
2. It pisses people off. This is the opposite of your goal of building relationships with customers.
3. Your message will be marked as SPAM. If too many people mark you as SPAM you won't be able to send email anymore.

Don't do this:

"To be removed from non-essential mailings and announcements like this, log into your CPanel and click on the Profile/Billing tab - under Customer Preferences change the Receive promotional mail setting to no and click save."

Yes, I actually got that in an email the other day. It is much easier for me to click the SPAM button and never have to deal with these knuckleheads again.