Summary (TL;DR): if you look for "correspondance backgammon" and you don't mind having nothing else (no PR matches, no fancy UI), then DailyGammon is what you need.
One of the curses of the Internet these days are clickbaiting articles like "3 reasons you need to do this" or "5 best somethings". But, well, there are three reasons why I love DailyGammon since I finally found it (took me a long time), so I'll list them here and risk that you think "OMG clickbait!"
Before I start, let's get a few things out of the way: UX-wise, DailyGammon can't hold a candle to state of the art sites like Backgammon Galaxy. This is what it looks like:
And there's no drag-and-drop moving, no animation in seeing what your opponent moved (instead you get beautiful pink arrows) etc.
Also, other than Backgammon Galaxy or Backgammon Studio Heroes it doesn't really advance what online Backgammon can be (e.g. have "Extreme Gammon" watch over your game, rate your strength, so you play not only for winning matches but also for the lower PR).
But that's fine. DailyGammon is excellent at one thing: offline (asynchronous? correspondence?) backgammon. And this is what I love, for three reasons.
1. I can finally play 7pt, 9pt and even 21pt matches
I love backgammon and I'm trying hard to improve my skills. In a position I try to find the best move, and sometimes this takes me a minute or so. And this is a great minute, weighing the alternatives, trying to keep pip count in mind, think whether offensive or defensive play is the right way forward, imagine what might happen after I moved, look for duplications etc.
The problem is that this way a 9pt match will take an hour or longer, which is not the amount of time I usually have in one sitting. My day allows for five minutes of backgammon now and 15 minutes then.
Unfortunately unlike in Chess, correspondance Backgammon is not a thing. Most sites don't support it. But DailyGammon does :-)
2. I can play relaxed matches
Maybe that's just me, but even "casual" games on Backgammon Galaxy cause my adrenaline to flow madly inside my body, causing my mind to miss great moves. Maybe I'm just not a "strategical thinking in high time pressure" guy, and maybe that's just me (on lichess my correspondence rating is 600 ELO above my blitz rating ...)
3. I can actually finish 7pt, 9pt and even 21pt matches
This is where DailyGammon really shines. The guys behind the site have clearly thought deeply about how to do correspondence backgammon and came up with an ingenious solution to an obvious problem. Other than chess or go, Backgammon has plenty of situations with obvious or forced moves. Opening DailyGammon, going into a match, pressing "roll dice" and "submit forced move", and coming back an hour later or so is just not working out.
For this problem, DailyGammon uses a computer guessing mechanism - after your move it rolls the opponent's dice and makes the most reasonable opponent move. Then it will ask you "if your opponent would roll this and move that, how would you continue?". This way you play a main variation for 3 or so moves before submitting your move.
When your opponent logs in later he can instantly play this sequence until he decides for a different move than what the computer thought (or until he doubles). If this happens, the rest of your pre-moves are rolled back, and the game continues (with different dice rolls then).
This speeds up the game dramatically. You can finish a single game in a few days.
The flip side of the coin is that things can get a bit confusing, and that chatting is tricky. Suppose you're playing five games at the same time. In game #3 you make a move, and then do 3 more moves conditionally based on what the computer thinks your opponent will do. Then you move to game 2, then to game 4. Then your opponent of game #3 comes and makes a different move for move 2, gets different dice afterwards. You come back to game 3 at a state that you just don't recall. Also, chatting "well that 66 was fairly lucky" is tricky because this might be move 3 of such a conditional move sequence, and if your opponent moves differently one move before he might never roll that 66 and not get what you're talking about.
Actually in my first game I clicked one move wrongly and submitted the move which was the third one of such a sequence. As the move I clicked was really stupid I chatted "oh well mouse click, meant to play that move". My opponent played differently, my wrong move never happened, my opponent was confused about what I'm writing...
4. (bonus reason): The people there seem to be more polite than on other sites
With Backgammon being Backgammon, the game where normal people rage-review apps because they can't bear being destroyed by superior engines (THEY CHEAT FOR SURE!), it's easier to come across inpolite language in Backgammon chats. So far I have the impression that on DailyGammon the crowed is more polite than on most sites.
