Feng Linhu was a little anxious because Li Yunfeng hadn't replied to him for a long time after he had sent him a letter, which made Feng Linhu anxious.
At this moment, a spell message suddenly flew directly into his window and fell into his hand. Feng Linghu couldn't help but feel happy. Then he immediately put his spiritual power into the spell. As soon as he saw the content of the spell, Feng Linghu's face couldn't help but show more joy. He then made the spell disappear.
This was the way to communicate with spells. It was not like a Jade slip. If you didn't want others to know, you could set a restriction in the Jade slip that others couldn't open. However, this method was not very safe. If you met a strong person who had a strong control of mental power, he might be able to break your restriction.