Hi, --On Thursday, March 7, 2002 10:49 AM -0600 Amos Gouaux <[EMAIL PROTECTED]> wrote:
| tjk> Problem: Management wants a return receipt feature for emails. | | For what, read receipt or delivery receipt? For delivery receipt, I | wonder if that's something lmtpd could do? Isn't read receipt | something the mail client would do? | | Though, if delivery failed the message would be bounced, so the | sender *should* know from that whether the message has been | delivered..... There are two kinds of receipt in email that you can use: 1) Message Delivery Notification (MDN) - this consists of a set of headers added to the message by the sender, indicating that they want notification of when the message is processed (either read or deleted) by the recipient. The recipients client is in charge of sending back the receipts. Clients that support it usually have the option to turn it off, prompt before sending, or automatically sending the receipt. It seems like the majority of people turn it off! 2) Delivery Status Notification (DSN) - this consists of some optional parameters added to the SMTP protocol exchange between the client and the SMTP server. Clients can request DSN's for success, delay or failure, and specify whether they want returned just the headers or the entire message body as part of the receipt. In order for DSN's to work properly, each SMTP server that handles the message enroute to delivery must support the DSN extension, as these options are passed along with the message. Usually if a DSN-aware server has to pass the message on to a non-DSN-aware server it will send a receipt back to the sender stating that the message got that far. A DSN success only guarantees that the message got delivered into the recipients INBOX - it won't tell you anything about whether the recipient actually sees the message. I think the DSN extension is pretty widely deployed in SMTP servers so this ought to be a fairly reliable method, though sometimes firewalls can get in the way. -- Cyrus Daboo
