I suggest having a recall option in outlook.com
There have been many times where I may send an email out of business hours then it has been rectified prior to the next business day where I am then unable to recall this email for them to be bothered with. It will also allow for any emails that you have written incorrectly or to the wrong recipient to be recalled, rather than 'undo' which only allows for a few seconds. I have been after this recall option for many years now and I feel it would be a great asset. After all, we are all human and do make mistakes, errors or do fix a problem after sending that email!