In this day and age of online marketing, getting the reason for a person unsubscribing is not just a "nice to have" but a necessity. Is there a way to do it with your system now? If not, hurry up!!!!
We agree this can be extremely useful information to catch. You can set your own unsubscribe confirmation page on your own site, so this way you can ask your subscribers anything you like and match it to your own brand for consistency.
Let's not forget that the subscriber really isn't under any obligation to let you know why either - it's definitely nice to know, but if they want to unsubscribe they might not be keen on giving you further information.
Fortunately with Campaign Monitor's instant unsubscribe they are removed right away, then you can optionally ask for some details, rather than saying you can't unsubscribe until you tell me why ;)