I've had a few requests to implement "delivery notification" when sending messages.
Spent a bit of time investigating, not sure what to do.
- Delivery notifications can be requested with the outgoing mail server at the time of actual sending (submit).
- It's an optional part of the SMTP spec, only some servers support it.
The above is for SMTP, Internet mail.
Exchange always supports delivery notifications, and it it finds itself passing your message to another mail server "in the outside world" which doesn't support delivery notifications, it generates a notification itself ("hey, I've done my part, forwarded your message to the mail sever handling @foo.com, where you recipient is, but have no idea how it's going to go there").
Since it's possible to switch accounts in Aqua while writing a message, and since a particular mail server's delivery notifications support can, in theory, change at any time, it's kind of difficult to know up front if it's actually going to work or not.
How do "all those other apps" handle it?
I did some tests in Thunderbird, which has this option when composing -- and when sending via an SMTP server that doesn't support delivery notifications, well, the message sends, but there will not be a delivery notification.
This may not be what the user expects ("why did I get the response from a human and never got the delivery report?"), and may become a support issue.
The alternative is to treat this as an error, so a message will not send and there will be an error notification in the status bar (and under the message itself in the drafts folder).
Any ideas?
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The above is only for "delivery reports" (which are automatic, handled by the mail delivery system itself, when it supports this) -- not "read reports" which Aqua already supports when sending and will support on the receiving side too soon.