A few days ago I posted some key rules for email broadcasts.
I wanted to expand on one of these (quoting myself):

5. Unsubscribe. Very easy unsubscribe, at bottom of the screen. In most cases, they now offer a “partial unsubscribe” such as to receive emails less often, or on fewer topics.

In sales and marketing, if you ever offer people only two choices “yes” or “no” you are going to lose a large number of “maybes” that could become “yesses” with a little work.
This comes up all the time. Example: If the only way to contact someone from your website is a single contact form, the visitor is given only one choice. Communicate that way, or don’t communicate at all. What if they want to communicate, but just not in that way?
Don’t brush this off as a minor point.
This is VERY common situation.
One of them, which is huge, is email subscriptions. If a person only has a choice of subscribing or not subscribing, you are likely to lose them over anything they don’t like.
That can be too many emails, emails on subjects they aren’t interested in, other things.
The answer which has become increasingly common is to let people modify their subscription without unsubscribing. You can let them specify how often they want to receive emails (maybe they don’t want weekly emails, but monthly is fine). You can let them specify which subjects they want newsletters on.
Of course you have to have an email program that supports these choices.
I just unsubscribed from one newsletter because it wasn’t sufficiently fine-grained. Yes, it offered options. But one of them WASN’T to stop receiving advertising only emails. It wasn’t worth it to me to be barraged with advertisements for things I wasn’t interested in, to get the occasional interesting article.
Think about it.