The code we run in production is all available to anyone who wants to play with it, though the usual caveats about "it's not particularly well tested for any configurations other than exactly the one we run" apply.
https://github.com/brong/cyrus-imapd/branches/fastmail
brong@prin:~/src/cyrus-imapd$ git log --oneline cmu/master..HEAD | wc -l 632
brong@prin:~/src/cyrus-imapd$ git diff cmu/master HEAD | diffstat | tail -n 1 149 files changed, 39060 insertions(+), 4314 deletions(-)
[1] http://blog.fastmail.fm/2012/10/18/changes-to-fastmail-servi...
In order to do that, we would have to hold all outbound emails until a delay threshold was reached... I'm not sure if that's a good idea.
I don't ever find a need to undo an email though.
I believe it was only for like 20-30 seconds as well that it offered undo.
| Gmail has it as an option
Here's a screenshot from Mail.app: https://files.app.net/1/79773/aTOWGMJ-rQ2Js_Edg-CWLi5FsLEVYq...
I either never knew that existed when I tried Mail.app with Gmail or it didn't work. In any case, it works perfectly with FastMail's "Archive" folder.
In our web interface, there are two buttons - one moves to Trash, the other to the Archive folder.
In terms of additional features:
- Support for Sieve scripts - LOVE this http://en.wikipedia.org/wiki/Sieve_(mail_filtering_language)
- Way faster loading time, snapper interface
- Lots more customizability (look at the display settings for an individual folder: https://files.app.net/1/79748/aXTHb4q16UPxgBvF2RCedd9jMSV2u4...)
- Some different interface features that I really like (your mileage may vary), like always showing starred messages on top for specific folders
There's lots more in terms of customizability and different weird configurations they allow you to do. They've done a pretty good job of hiding the complexity for non-power users, but it's still really accessible if you're willing to read through lots of preference screens.
There are some features FastMail does not have that Gmail does. The two big ones for me are undo send and composing in a new window (although you can just open the whole FastMail interface in a new tab and it only takes a second to load; opening Gmail in a new tab could take 10+ seconds in my experience). I use the FastMail web interface full time and am just as efficient, if not more, than I am with Gmail. The keyboard shortcuts are pretty much the same, so there wasn't even a learning curve.