Exchange license contains SMTP so you’d only need to purchase Exchange. This is licensed per mailbox. I’d say it’s little bit expensive (of course depends on the size of your server).

Here’s the purchase link: http://www.shareit.com/product.html?cart=1&productid=196385&languageid=1

The drawback is that the shop will probably not recognize that you’ve already bought the Server Edition so it will issue a new license file that will contain just the Exchange Server Edition license. But if you send me those two files (the original Server Edition license that you already have and the new one for Exchange Server Edition), I’ll merge them for you… :slight_smile:

Thanks
Vlk