This parameter is used for S3 and SES only. The AWS account ID (without a hyphen) of the source owner. For example, if the SourceArn identifies a bucket, then this is the bucket owner's account ID. You can use this additional condition to ensure the bucket you specify is owned by a specific account (it is possible the bucket owner deleted the bucket and some other AWS account created the bucket). You can also use this condition to specify all sources (that is, you don't specify the SourceArn) owned by a specific account.