There’s a Kickstarter just opened for an Apple Mail plugin that will add send later and undo send features. (I have no affiliation but thought MPUers might be interested.)
https://www.kickstarter.com/projects/pierreparissi/send-later
More info here: https://www.send-later-mail.com
MailSuite has seveal configurable send-later features.
I’ve seen “recall send” implemented in email clients over the years – it is not reliable, and tricks people into thinking that somehow the software will reach into the recipient’s mailbox and remove the message, which doesn’t happen.
I occasionally use this in Gmail, but requires using the Gmail app.
Thanks for the heads up, @prc.
I’ve been using the Undo Send and Send Later features in Mailbutler for years and find that they consistently work well. Mailbutler also has a Chrome extension that makes it possible to tap into this and other functionality when using the Gmail web app.
Both Send Later and Undo Send hold your outbound message in the Mailbutler client. Once a message is transmitted an email client cannot call it back.
At one time Microsoft Exchange Server did have an “undo send” feature that allowed you to recall a message sent to someone on the same server, if they had not opened it. (MS may still offer this but we got rid of Exchange around 2002)
Exactly. It just adds a buffer between pressing the send button and the message actually being sent (I have the delay set to 10 seconds). I’ve found this to be surprisingly helpful. In fact, it feels now feels weird to use an email client that sends messages right away.
At one time Microsoft Exchange Server did have an “undo send” feature that allowed you to recall a message sent to someone on the same server if they had not opened it. (MS may still offer this but we got rid of Exchange around 2002)
Interesting. I vaguely remember seeing internal email services that had the ability to remotely delete unopened emails that had already been sent.
I think we’ve all wished for a feature like that at one time or another. My solution is to always compose important messages in BBEdit/TextEdit then paste the results into email.
It takes a few extra seconds but can eliminate most of those “Oh (explicative deleted)!” moments. 
Mailmate has this built-in. You can set a default delay-before-send and/or set it individually.
I have it set for 3 minutes. Anything longer I send as a scheduled email using Gmail’s web interface.
Yup, that’s the way it was at work. And you would get a message saying something like “this mail has been recalled by sender” if you weren’t quick enough. Then we’d have to run around and see who had already viewed it so we would know what it said anyway. 
It’s also helpful if you’re communicating with clients. If you have time to answer an email at 10:00 pm, you can do it and schedule the send for first thing the next day so you don’t create the expectation of you answering their emails at 10:00 pm. 
I love that feature for exactly that reason. It is also good at scheduling a response to someone who will, if you respond right away, send another email that expects a response. You can lose a lot of time that way, but if you schedule your reply for 2 hours later, it helps break that ‘email circle/chain’
I just sent an email that I was fairly anxious about sending - I’m kindof happy there wasn’t the option to pull it back and I just had to hope and pray it would be well received.