Does it make sense? In either direction? Of course not, even if one is just discussing email.
Go ask The White House if it was worth it.
Unless your job as CIO depends on having a major project under your belt and you figured this is easier than implementing SAP you are just wasting your companies money and that is just not a good reason to do anything.
Shame on you if you are that type of CIO. But your CEO is probably like that as well so you are safe, sadly, for the year or 2. And if you are that kind of a person please let me come in as your understudy, I promise to give you all the credit you are due but move the company forward once you leave as well.
It does not make financial sense from almost all angles.
You still need admins, servers, networks, firewalls, licenses, support, etc.
Yes one could argue there is a long list of Microsoft products required to do what one Domino server does, but that is not the issue for the moment, if we are truly discussing only email.
Does it really make sense politically? Yes there are Microsoft and Lotus evangelists and we love our jobs and possibly as well too much our respective companies.
The problem is what happens when you get in the middle.
Is it politics that dictates wasting a million dollars or 5 just because of a UI? Or a personal hatred of IBM or Microsoft or Sun or Oracle?
Sure Outlook is unimpressive, it's 5 years old, unless you use office 2007 and then what is so exciting about it, the ribbon? Yes the Notes client looked about the same for the last 12 years but the R8 client really is very different and more functional than Outlook, as discussed in a previous post.
You could train the users in the new product.
Stop laughing everyone reading this. Some companies do believe in training, they just tell you to do it on your own time. Pay for training is almost unheard of today.
Does it make business or operational sense? Will either one help you go forward faster, see an ROI or allow your sales force or manufacturing plant or research staff to be more productive faster? That is the key question in my mind, one which I have held since around 1991 when I first not only experienced Notes but started working on Windows 2.
If, in a 10,000 user company you can replace Domino with Exchange for email at the same price as it costs you for Domino, maybe you have a winner bet there. Although if you wanted to go from Exchange to Domino you would see an immediate ROI and cost savings. It just costs less to not need CALs for every piece of software and licenses, all esle being equal.
But I am quite confident it is not possible to save money moving to Exchanegf rom Domino and in this age where economics are out of line, budgets are in limbo from quarter to quarter if not week to week, you want to push through a swap of your email system you either have too much time on your hands or too much money because I can think of better ways to spend that money... and so should you.