How is it supposed to work, when you get one of those emails whose body reads 'Sender Name would like to recall the message, "Subject Line"'?
I assume some mail system like Exchange is supposed to find the matching previous message and delete both. And my normal Unix mail system doesn't.
But how does it decide on the matching message? I can't find any header that unambiguously identifies it. No 'Recalled-message-id:' or similar. How does a system supporting this feature make it work?
@simontatham I assume that, for systems that support it, there's an proprietary non-SMTP way of doing it that identifies the exact message but, when interacting with SMTP-based mailservers, they just did the absolute minimum and fall back to sending a simple message because shrug what else can you do?
@cawhitworth well, what else you could do would be to include a sensible amount of information in the courtesy notification, for exactly the reason I suggest!
All I have to go on is the subject line of the recalled message, which is no help when the recaller promptly sent me a redrafted version with the same subject line. Now I have to look at the datestamps to guess which was the latest draft. (And probably make sure I'm looking at the sender datestamp.)
Anyway, uh, I work for the company that makes Exchange so I had a dig around. I found a dev spec for message recall in OWA and while the transport is proprietary, there's definitely an identifier in the recall message payload you could put in the SMTP headers too.
(I suspect the reason why they didn't is somewhere between "did the bare minimum for interop" and "if you want this to work properly, pay for Exchange")
@cawhitworth "pay for Exchange": I can see how a company might have that attitude (whether I like it or not!), but does that square with @andrewg's comment elsethread that recall only works within the same Exchange server? If that's true, then even paying for Exchange doesn't make it work properly.
(Not that you'd necessarily want someone in Org A to be able to destroy mail on Org B's server, but as before, at least identifying it would still be practically useful.)
Motivation: even if you don't think it's a good idea to actually implement deletion of the linked message, it would at least be nice for a mail system to tell you which one the linked message is.
If someone sends me N very similar messages and N−1 recall attempts, suggesting that they kept redrafting it after pressing Send, I'd like to at least be able to tell which version they want me to reply to, even if I haven't actually deleted the superseded drafts.
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