Bitcoin Forum

I initially posted this in 'trading', but I'm not sure if this would be a better category.  Is there any api call/sign-up/mailing list that will let you know when a coin is going to be listed and/or when it is going to be delisted?

Whenever there is some delisting or listing, I am staying in this forum for some news and there is another thing, try to listen to the updates of that particular exchange and propably you can see their updates on the listing/delisting of coins.

Your best bet would indeed be to stay around and keep watching the bitcointalk thread for news and info, telegram or even irc.

If you are registered on the exchange, usually they will send out an email informing of any listings/delistings.  You can also follow their twitter account. 

the best way of getting updated in all the coins listed / delisted by following their on thier telegram website  checking it the market news, social media and follow their updates.

But looks the twitter account gives the actual update about it. Look at binance and how the twitter account was actively update the coin that will be listed on the exchange site. And i remember about polo and bittrex was doing the same too. and then the exchange will try to send the notification through user's email

I dont think that we will get information from exchanger about listing or delist altcoin.
I never get any information through email about listing and delist.
Follow twitter is better i think.

Usually i just take a look at coinmarketcap, however check ann thread at altcoin section is fine because there will be a ton of announcement about new coin

Find an exchange telegram account and join. Do not mute them.

Quite bad I don't know anyone now.

I usually stay updated when a coin/token is listed in CoinMarketCap. When I go to their website, I just go to their "Recently Added" section where I can see the latest ones being listed in the market.

As for delisting, I'm not sure yet. I just have to follow their social media accounts to see if there are updates about delisting. Anyways, I also feel that some of the coins to be listed are lending types like Bitconnect and Regalcoin.

Yup, check coinmarketcap (https://coinmarketcap.com/new/), follow the news / emails of your exchange(s) and keep track via social media and bitcointalk of course.