Can Zimbra be an SMTP server? POP, IMAP, Spam controls, etc.

I've been reading about Zimbra but it cannot confirm if it could be used as a stand alone SMTP server?

For many years, I've been using traditional SMTP servers for multi-domain hosting but when I came across this, I thought how interesting would it be to change out the SMTP server for something with so much more to offer.

I would need all of the usual SMTP functions, POP, POPS, IMAP, IMAPS, webmail and full spam control by it's users.

Anyhow, would love some input, thanks.

Mike