How to annoy a potential customer

Just over two years ago I opened an account with Regfly.com to enable a transfer of a domain name to our business.

Once the transfer was completed I moved the domain name to our registry.

After this transfer I received no further emails from Regfly.com then this last two months I received two emails from them saying how they appreciated my business.

Thinking I might have left a domain on their service by mistake I checked but found none. I thought I should close the account so that I didn't get any further emails.

However this proved impossible and I was told by their tech support that this couldn't be done.

So what lessons does this hold for how you treat your customers:

• If you haven't had contact with customers (or previous customers) on your database don't assume they will want to hear from you.
• Ensure you provide a means to opt out of your system and if they ask to be removed from your system simply do it. 
• In every email communication offer a simple means to be removed from your system. It should be a one click system ideally
• The longer the gap in communication the more likely the person won't remember dealing with you.
• Of course this rule applies not only to emails but phone, fax and postal communications.

Have you any experiences like this to share? Feel free to comment below.