Is a blessing letter in WeChat sent to the other party's mobile phone by SMS?

No. Wechat is an Internet-based communication tool that can send various forms of information, such as text, pictures, voice and video. Wechat can also send short messages, but a wish letter is more a way of blessing or expressing one's mind. A blessing letter from WeChat is usually sent to friends or relatives through WeChat chat function, so the blessing letter from WeChat is not a text message. A short message refers to a short text message sent directly by a mobile phone.