WalterH crpb The 'Recall' feature has been part of Exchange for quite a while. Over the years I have used it, occasionally, to recall messages which have accidentally been sent before the mail writing was completed (accidental click on Send or pressing Return when the focus was not in the mail body). This has worked on local delivery, and I think remote delivery if the remote server was an Exchange server, but haven't used this for some years now. However, I am aware if the recipient allows delivery receipts the recall will fail as the recipients server will have processed the email.
I suspect that when @WalterH was able to recall a message from a mobile device this was a feature called something like 'undo send' that is implemented in the mobile mail client. Apple implemented the feature in IOS around IOS14/15. It appears to delay the actual sending of the email from the client to the outgoing mail server (message is held in the outbox of the client). In IOS 17, the feature is sort of programmable, by setting the delay Apple Mail uses before sending the email up to 30 seconds. You can access this by opening settings, locate Mail, then at the very bottom of the options you will find 'Undo Send Delay'. Whether 30s is long enough to realise you need to recall a message is a mouse point but the feature does allow for catching incomplete emails being transmitted.
For those who are interested Apple extended this feature into their messaging app (a while back) and it is now also possible to 'Undo Send' for text messages as well (again only a fairly short delay period is allowed). After sending the message if you press and hold on it in the client it will allow recalling the message for a short while. I suspect that other mobile platforms will also have implemented a similar feature by now.
Best Regards
Mark
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