OH GOODNESS! My votes... top post etiquette ridiculous, reverse name lookup dangerous (but I like it).
My first impression is that you all meant that the @domain.com has to have a reverse lookup, which I hope everyone knows would be catistrophic since only the machines themselves will typically have lookups. Virtual domains rarely do. So I hope this isn't the case. But if you are talking about doing a lookup on the machines domain name that should work out fine as long as it doesn't have to match just have a positive result. For instance good old Inter7 here uses evanston.inter7.com but has a reverse lookup of mail.inter7.com. If the original poster is forcing it to match he wouldn't get his emails from Inter7. Now back to assisting that original poster and myself. Can someone please tell us how to implement the reverse name lookup hack? It should verify the machine name and not require a match just check that is actually has a lookup. As for sending an error back to the server isn't that a little useless? If we are not accepting because the server really isn't there then where do we expect the error to go. Or are we just sending the error back to the client? Lets turn this into a productive post please. If I wanted to see a bunch of flamage I would subscribe to a MicroSuck list. Wil Hatfield