On 2007-01-23 16:27:12 -0500, Eric A. Hall wrote: > On 1/23/2007 4:00 PM, Peter J. Holzer wrote: > >> MTA-resident complex content filtering with different per-recipient > >> outcomes is not compatible with recipient enumeration preceding the > >> data block; > > > > It can still be done. It just needs a bit of trickery with 4xx replies. > > It's ugly as hell, and it increases mail traffic (and CPU usage for > > filtering), but it works. > > see http://www.ehsco.com/misc/I-Ds/draft-hall-inline-dsn-01.txt which uses > per-recipient codes after the data block (the LMTP model) I meant "it can be done without extensions to SMTP". With extensions it can be done in a much cleaner way, of course; but that needs support in both the client and the server. A few quibbles about your draft (which I'm tempted to implement in qpsmtpd if someone implements the client side): The name INLINE-DSN doesn't describe well what it does. To me, a DSN is more than an SMTP reply, it's an entire message explaining what happened to the mail, and your extension doesn't send that. Something like DATA-RCPT-RESULT would be more descriptive (not that an SMTP client will care much about the meaning of the bytes it sends). I'm a bit dubious about the use of 3xx status codes. In the other cases where they are used (DATA, SMTP AUTH, ...) they are used to indicate to the client that it should send more data to complete the current command, not that it should send another command. It's a clever way to defer only some recipients until after data, though. Finally a question: How is it determines which of the response codes after DATA corresponds to which recipient? Do they have to be in the same order or do they have to include the recipient address? Your examples show both, but the text isn't clear. hp -- _ | Peter J. Holzer | I know I'd be respectful of a pirate |_|_) | Sysadmin WSR | with an emu on his shoulder. | | | hjp at hjp.at | __/ | http://www.hjp.at/ | -- Sam in "Freefall"
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