Methods and systems are provided which convey access control information from a first server to a second server through an end user device, for example in a system in which these servers and devices are all connected to the Internet. The method starts after the first server receives a message from the end user device. The first server in response to this message from the end user device sends a response message to the end user device containing the access control information to be conveyed to the second server, optionally after performing authentication. The response message also contains an instruction for the end user device to post a second message to the second server containing the information. The information is preferably contained in a content portion of the message. A hidden form may be used in the response message to contain the information. Optionally, the end user may be presented with an option to post the second message or not. This may allow conformance with data privacy laws requiring end user consent of data transfer. The instruction to post to the second server may consist of active content within the response message's content portion. This can be used to cause an end user device to store a cookie in association with a number of servers in different domains thereby implementing a multiple domain single sign-on function.