messageGroupId

The MessageGroupId can contain up to 128 alphanumeric characters (a-z, A-Z, 0-9) and punctuation (!"#$%&'()*+,-./:;<=>?@[\]^_{|}~)`.

For FIFO topics: The MessageGroupId is a tag that specifies that a message belongs to a specific message group. Messages that belong to the same message group are processed in a FIFO manner (however, messages in different message groups might be processed out of order). Every message must include a MessageGroupId.

For standard topics: The MessageGroupId is optional and is forwarded only to Amazon SQS standard subscriptions to activate fair queues. The MessageGroupId is not used for, or sent to, any other endpoint types. When provided, the same validation rules apply as for FIFO topics.