[Feature Suggestion] Undo sent email

[martgil]

Some users are requesting an "undo sent email" feature in FlowCrypt.

Reference:
https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzQVzNwflrKXqBwcQwcFNFmmgXGZ
https://mail.google.com/mail/u/human@flowcrypt.com/#inbox/FMfcgzQZTCfCbJpxzlvcfwBvBqrCpTDx

[martgil]

We can imitate how Gmail tried to somehow implement this by having a delay (grace period) before the sent email gets actually sent (3-5 seconds - configurable). This enables sender to stop the ongoing process of the sending emails when needed.