Confirmation emails might be useless, but notifications of new features are not spam.

I generally get annoyed at sites that keep emailing me about new features. I always unsubscribe or opt-out at sign in, but some people don't offer that feature.

Yup. If they don't let up, I mark those emails as "spam" in my Gmail. I guess that counts against them.

They should have a "Don't mail me bro" checkbox. I don't always agree with their definition of "spam".

Yes you're right - this was just off the top of my head...

There might of course also be other valid reasons for wanting an e-mail adresse.

Yeah, for example uniquely identifying users.

You can do that with a username....

True however then users have to think followed by get frustrated dreaming up a name. They already know their email address. And unless they already signed up its probably not taken.

I think the frustration of entering your email, checking you inbox and following a confirmation link is a lot more than the frustration of dreaming up a name - which you have to do anyway unless you use your email as a login.

I think that the metrics support this view as well.

An ability of directly communicating with your users has a very positive effect on a valuation of the company. One thing is when you have N million User IDs, and another - N millions emails.

Also if you are running a service with termed licensing, an email communication is how you drive the license renewal process. This sort of communication does not qualify as spam, because it is more of a service reminder rather than an unsolicited commercial offering.

I see your point, and of course you are right that it drives your valuation upwards if you can engage in a genuine conversation with your customers.

I was referring more to the sign-up stage though, where you tend to lose a lot of potential customers with obligatory confirmation e-mails.

But if you can get the conversation going after the critical sign-up step, you should by all means do so.

The other legitimate use of email is for actual features that use email-- internal messaging, invitations, notifications, reminders, etc.

All your users have it-- have you thought about when your users might like to be notified about new activity relating to them? (opt-in, of course)

You're absolutely right - this is a good reason for having a users e-mail. There are probably many others as well.

You just shouldn't request an obligatory email adress, or even worse a confirmation by email, unless you really have to. It tends to scare a lot of users away.

Exactly. The business metric of email lists will keep them from going extinct.