Undo send would be really hard!  But undo in other areas is possible, provided that the email servers support the command.  For example, Gmail (through IMAP) does not support undo delete.

Command+Z (Mac OS) to 'Undelete a message' (when I've just deleted one, or a thread) seems to work for me. At least it achieves what I expect, which is the return of the message to the folder I just removed it from.

What's different? (Obviously I have it set to flag a message as deleted in the IMAP mailbox, and move it to the Trash folder.)

why do I feel like I'm the only Windows Postbox user out there? ;-) On windows, ctrl-Z (or selecting Edit > Undo Delete Message) have no effect.

and, hmm, ditto what James said-- I don't know about official IMAP undo-delete support, but isn't undeleting a message just moving it from the 'Trash' folder, back to the folder you are looking at?

Undo send needn't be conceptually hard if a local queue were to be implemented with an arbitrary delay enforced before messages in the queue are actually dispatched (thus providing a window of time in which the decision to send can be later rescinded). Not that I'd personally find the feature useful, nor that the coding would necessarily be easy, but as a concept I think it is straightforward enough.

I would love access to both features the OP mentions.  @Kerin's would be a fine implementation of "Undo Send" and, I suspect, how the Gmail labs feature accomplishes its magic.

On a related note to what's being said above, I'd love an "outbox" where mail would be gathered but wouldn't send until I wanted it to do so.

As for Undo, even easier than having a local queue with a delay-- just store a note in the undo buffer with the last move action ("message #x was moved from folder #y to folder #z")... then undoing is simply a matter of moving it back.

(Isn't it fun when users try to give you specific details about how to code your app? hehe... ;-)

FWIW I'm still mad about Postbox and it's my #1 email client on both of my primary machines!

best-- Eric

I really miss being able to undo delete. (esp when that really means just moving it to trash)

I tried it again, just now, with Postbox 1.1.4 and an undo (Command+Z) of a move-to-Trash deletion (for a mailbox on an IMAP server) put the message exactly back where it was.

Is it just not working on Windows? Or with a particular type of mail server?

It mostly depends upon the email server.  If the server supports undo, then generally undo should work within Postbox.

I really wish this worked within GMail (it doesn't)

I also use the Gmail "Undo" feature all the time. It is not really an undo feature, as Kerin points out above. I do not believe it would be hard to implement if you supported "Send Later" in general. In Google Labs, you just tell it how many seconds after clicking "Send" you want Gmail to wait before actually sending your message. I use keyboard shortcuts a lot, and I sometimes do the wrong thing at the wrong time and send a message before it is done. By having 10 seconds to say "Oops, grab that before it goes out" I save a lot of embarrassment. 

Outlook (and I hear Eudora) does a flexible job of allowing you to say you don't want a message to go out until a particular time. This can be nice if you don't want to bother people during their workday, etc. Again, in Postbox this might all be done with simple expansion to an Outbox in which to queue messages (while on the plane, for example), grab them before they go out (when online), or adjust their "Send Later" parameters.

The Outbox could also facilitate the sending of mail in a background process as described here: http://support.postbox-inc.com/entries/90199-feature-req-send-email... because you could hand the message off to the Outbox and then return to work. It could then be sent in the background immediately, sent at a specific time, or sent after a short delay so that you could stop it going out if needed.

In the spirit of circular reference, this post suggests just the delayed send feature, which is what is really just a variation on the Undo Send feature being discussed here: http://support.postbox-inc.com/entries/144043-add-a-delayed-send-op...

I just want to be able to restore a message after it is moved to a different folder.  Examples of when I try to use this (but it doesn't work is): 1) Accidentally drag a message to the wrong folder 2) Delete a message and want to undelete it 3) Archive a message and want to unarchive it.

It is really annoying that this doesn't work with GMail.

A way to incorporate an Undo send.. is have an optional delay before a *sent* email is physically sent... it just sits in the queue till the timer expires... Ideally it be user configurable to enable it (send immediately would have a value of 0 or 1, while the delay would be anywhere from about 3-10 minutes, depending on the users preference....) If the user deletes or somehow tags the message in the queue it will not be sent out...