It's all about the fun
Ok, so you get some people subscribed for your daily deal email. But how will you keep them subscribed?
A regular person is very unlikely to buy coupons for every deal you post. They may like one deal or another once in a month, but will inevitably pass on the rest of the deals. And if they get yet another email with the deal they don't like, unsubscribing is only one click away.
Of course, you would rather keep your subscribers engaged, so even if they did not like today's deal, they are still eager to read your email tomorrow morning. So you must provide some entertainment for your subscribers to stay on.
If your deal descriptions are short and to the point, people will get bored pretty soon. Much better if your deal descriptions are fun to read, provocative and amusing.
Tell a fun story only tangentially related to the deal, bring an obscure curious fact, throw in a few jokes. Sure you must mention key deal details and emphasize its highlights and restrictions. But don't make this boring part too big. Only if people like your story, they will share it with their friends.
Of course, writing good prose is hard and requires skills and practice, so it's not for everyone. If you cannot write good articles yourself, consider hiring a freelance copywriter. Just make sure the style is right for your audience. Keeping light and upbeat tone is a good start.