Message bodies were initially limited to 8KB in size but was later raised to 64KB on 2010-07-01 and then 256KB on 2013-06-18. For larger messages, the user has a few options to get around this limitation. A large message can be split into multiple segments that are sent separately, or the message data can be stored using Amazon Simple Storage Service (Amazon S3) or Amazon DynamoDB with just a pointer to the data transmitted in the SQS message. Amazon has made an Extended Client Library available for this purpose An extension to the Amazon SQS client that enables sending and receiving messages up to 2GB via Amazon S3. : awslabs/amazon-sqs-java-extended-client-lib. The service supports both unlimited queues and message traffic. SQS does not automatically delete messages once they are sent. When a message is delivered, a receipt handle is generated for that delivery and sent to the recipient. These receipts are not sent with the message but in addition to it. SQS requires the recipient to provide the receipt in order to delete a message. This feature is new as of 2008 where only the message ID was required for message deletion. Because the system is distributed, a message may be sent more than once. In this case, the most recent receipt handle is needed to delete the message. Once a message is delivered, it has a visibility timeout to prevent other components from consuming it. The "clock" for the visibility timeout starts once a message is sent, the default time being 30 seconds. If the queue is not told to delete the message during this time, the message becomes visible again and will be present. Each queue also consists of a retention parameter defaulting to 4 days. Any message residing in the queue for longer will be purged automatically. The retention can be modified from 1 minute up to 14 days by the user. If the retention is changed while messages are already in the queue, any message that has been in the queue for longer than the new retention will be purged. Dropbox, Netflix and Nextdoor are examples of companies that use SQS extensively. SQS is also widely used within Amazon.com. The first 1 million monthly requests are free. After that, the pricing is as follows for all regions:  Data Transfer price