A common problem for users of NexentaStor, especially home users and people doing a trial evaluation of the software, is that, at least as of 184.108.40.206, it requires a real SMTP server somewhere else in order to send email. I'm often told no email was set up because no SMTP server or account was available (at home, this is often just permanently true, and in the enterprise this is often true during eval phases). This is bad - NexentaStor sends all sorts of alerts via email that it does not display anywhere else. Your appliance may be warning you of something, and you'll have no idea. There is a workaround, however, if the appliance can get to the internet and you have GMail (or can be bothered to set up an account)!
Simply set the server address to smtp.gmail.com and the username to the full email address of the account on Gmail, and of course set the password. Choose SSL as the authentication method, and be sure the 'From E-Mail Address' is set to the email address of the Gmail user (you don't technically have to - but Gmail will just use the actual from anyway, not what you set here, and I worry if you set it otherwise Google might eventually claim you're trying to spam through their service). And voila, you're all set. Here's a screenshot of the settings in the initial NMV setup wizard, just for completeness.