using executorService

HI,
In my spring web application there is a class like : 

[code]
@Service
class BotMessage {
    private ExecutorService executorService = Executors.newFixedThreadPool(1);
     public void sendMessage(message) {
     executorService.submit(() -> sendMessage(message));
}
}
[/code]

In another class : 
[code]
@Service
Public class PullService {
    private ExecutorService executorService = Executors.newFixedThreadPool(10);
   public void pull(Date date) {
        List<UserInfo> getAllUsers = userTokenService.getAllUsers();
        getAllUsers.forEach((o) -> {
                        pullGlobalNotification(o, date, accessToken);
                  }
}
}


 private void pullGlobalNotification(UserInfo userInfo, Date date, String accessToken) {
            GitHub gitHub = githubCache.getIfPresent(userInfo.getUserId());
            executorService.submit(notificationTask);
}[/code]

Now this notificationTask has a run function() {
for(int i = 0;i<10;i++)
botMessage.sendMessage(i.toString());
}

What i am wondering is since botMessage.sendMessage uses an executor with size 1.
now at i = 0 sendMessage will internally call  [b]executorService.submit(() -> sendMessage(message));
[/b]
At i = 1... Will the call to [b]executorService.submit(() -> sendMessage(message));[/b] block if the previous call is still running  as the size of executor is 1. Also will it get queued in the executor and the loop will still continue ? What should be the ideal size in this case.. As this function may be called simultaneously from various thread..

Also in the PullService class the size of ThreadPool is 10... Althought the number of users returned by userTokenService.getAllUsers();
may be more than 10.. In that case the further calls will block ? Also what should be the ideal size of ThreadPool to keep here.
Thanks