# FAQ entries tagged #Message

If you send a message specifying a user who has blocked the LINE Official Account or a user who deleted their account, no error will occur and status code 200 will be returned as a response.

In this case, no message will be sent to the user.

If a message is sent to a user ID that doesn't exist, this error will be returned with status code 400.

"message": "Failed to send messages"

Note that the user ID is a value issued for each provider. If you send a message with a user ID issued by another provider, it will be treated as if you sent the message to a user ID that doesn't exist.

For more information on user IDs, see What are the user ID, group ID, room ID, and one-on-one chat ID values?

Characters in a text are counted in UTF-16 code units (16-bit). Characters expressed in multiple code units, such as some kanji characters and Unicode emojis, are counted as multiple characters instead of one character.

However, some properties are counted in grapheme cluster (opens new window) units rather than UTF-16 code units. For more information, see Counting characters in a text in the Messaging API documentation.

Also, unlike Unicode emojis, LINE emojis provided by LINE are internally converted to the alternative text (e.g., (love)), so they're counted by the number of characters in the alternative text.

Examples of counting the number of characters in UTF-16 code units are as follows:

Character UTF-16 encoded value Number of code units Number of characters
a 0061 1 1 character
3042 1 1 character
\n 000A 1 1 character
908A 1 1 character
𠀋 D840 DC0B 2 2 characters
👋 D83D DC4B 2 2 characters
👋🏻 D83D DC4B D83C DFFB 4 4 characters

If you specify a user who doesn't actually receive the message, such as a user ID that blocked the LINE Official Account or a user ID that doesn't exist, the message won't be counted even if you call the API for sending the message.

The number of messages is counted by the number of people to whom the message was sent. In this example, if there are five people in the group chat or multi-person chat where you sent the message, the number of messages counted is five. The number of message objects specified in a single request doesn't affect the number of messages sent.

For message count when you send a message to a user who doesn't receive the message, see If I send a message to a user who doesn't receive the message, is it still counted as one message?.

For more information on pricing, see Messaging API pricing.

Yes.

If multiple message objects are set in the request body when sending a message, the messages will be delivered in the order they are set from the top.

Message IDs are assigned a value that is unique throughout the Messaging API environment.

It doesn't mean that it's unique for each channel or message type, such as an image.