Lots of people have pointed out several possible improvements to this feature. Now if we could anticipate these things with a few minutes of contemplation (each

Lots of people have pointed out several possible improvements to this feature. Now if we could anticipate these things with a few minutes of contemplation (each), I'm sure Google would have come up with the same list of gripes. But obviously, they did some tradeoff analysis and decided to do what they did. Now, from a technical standpoint, the fact that they implemented this feature in the present way results in some information of their internal infrastructure and engineering organization to leak through. The 5 second, non-configurable timeout should allow us to speculate a little bit on what Gmail's architecture is. The only reason I can think of is that maybe the undo operation results in a scan over all queued email for all users. This is obviously an expensive operation, so maybe they cannot easily increase this delay with their current architecture. They'll have to add per-user queues on their servers. Maybe that's too big an engineering project at present. What do you think? Microsoft Outlook has had a sophisticated version of this for a long time. I know a guy who had set up Outlook to send all his email 30 min after he hit send. You can even schedule a message for sending at an arbitrary time (i.e., per-message level granularity of send delay). For instance, the Microsoft Outlook implementation of this feature essentially implies that each client can queue up emails for later delivery on the server and later interrogate this queue in a sophisticated way (i.e., it's not fire and forget).