[asielen]

Have you ever worked with the general public? At least half of adults would fail at that basic task.

The point of a business is to make money. You make more money by making the experience for your customers as easy as possible. If you don't, another company will.

[CRConrad]

If someone wants to unsubscribe, that's probably because they don't want to be your customer any more anyway. Unsubscribing for a now-irrelevant-to-them e-mail list may be a problem for these ex-customers, but it isn't yours any more.