Do I get an error when I send a message with a user ID that blocks the LINE Official Account?
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.
Do I get an error when I send a message with a user ID that doesn't exist?
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.
How many full-width characters, emojis, line breaks, and so on, are counted in the text message character count?
The character count in a text message depends on the character type.
Alphabet/full-width characters: 1 character
Line break characters: 1 character per line break character (\n: 1 character, \r\n: 2 characters)
Emojis defined by Unicode and LINE
Emojis in Basic Multilingual Plane (for example, ☎): 1 character
Emojis on the supplementary plane that are represented using surrogate pairs: 2 characters
This includes emojis defined by LINE and Unicode.
If I send a message to a user who doesn't receive the message, is it counted as one message?
If you specify a user who doesn't actually receive the message, such as a user ID that blocks 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.
If I send one push message to a room or group with multiple people (for example, 5 people), how many messages will I be charged for?
You will be charged for the number of people in the room or group. (In this example, you would be charged for 5.)
If I set multiple message objects in the request body when sending a message, will the messages be delivered in the order they are set from the top?
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.
Is the message ID in the message webhook event object unique per message type or per channel?
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.