A much simpler proposal involving no new infrastructure and voluntary participation is presented in OMX.txt in this directory. The following text was written 12 May and remains here for historical reasons only (18 May 2003) discussion of submitting a IETF RFC for "outgoing MX" records of some kind has taken place. The outgoing MX record, wither a new DNS record type, or simpler, a designated TLD such as omx.int that would be maintained by IETF for this purpose, would list machines known to be proper origins for e-mail from a given domain. So, hotmail.com.omx.int would have a whole lot of A records in it, one for every outbound hotmail server. Or, it would work like the in-arpa TLD and the appearance of a record of any kind would indicate validity of the message source, so hotmail would have to add a DNS entry in the hotmail.com.omx.int domain for each of their servers that sends mail out. For instance if they are sending mail out through 65.54.252.99 (which is currently listed as one of the addresses for sending mail in to hotmail) they would need to define a record (PTR? A? why one and not another?) for 99.252.54.65.hotmail.com.omx.int; and the omx.int DNS would refer queries for net.domain.tld.omx.int to whatever systems handle queries for net.domain.tld, and missing records would get cached for a good while. I guess I could start by offering this service at .....omx.pay2send.com but I would rather see it at a more top-level kind of place.