I made that mistake 3 weeks ago.  After a sales associate asked me to sign me up for the card to get a 10% discount for my friend, I started to receive emails the next day.  I received an email each day until the 4th day I had enough.  I called up and asked for my email address to be deleted and I did not wish to be contacted.

“No problem buddy” he said.  ”It is effective immediately.”

Imagine my surprise the next day when I kept receiving emails about their online service.  I called back and explained how I had contacted them before.  ”Oh well it can take up to 7 days to stop.”  After that it will stop.

Guess what happened the next week?  That’s right, everyday they sent me emails.  A week and a day later I called back.  ”This is the third time that I’ve called about this issue.  I don’t wish to be contacted.  Please remove my email.”

“Of course sir.” the woman responded.  ”You don’t want to use your online account?”

“No. I just want to get the 10% discount.  Please just delete my email.” I asked nicely.

“If you do then you won’t be able to set up an account.” she said.  At this point I began to wonder if they felt their customers were stupid or if she was just reading from a script.

“I understand that.  I was tricked to give my email address.  What do I have to do to take it off?” I asked.

“Just a minute I need to put you on hold.” she asked.  She came back and said “Ok it’s removed.”

“Great.  Thank you very much!” I said.  Click.

I will never again give anyone my email address no matter if that is a requirement to receiving a discount.  I will just say I’m sorry to hear that and walk out.  Why do business force something that a customer doesn’t want? That is not a good long-term customer retention strategy.