sSMTP is described as 'simple MTA to deliver mail from a computer to a mail server. sSMTP is simple and lightweight, there are no daemons or anything hogging up CPU; Just sSMTP. Unlike Exim4, sSMTP does not receive mail, expand aliases, or manage a queue' and is an app in the Office & Productivity category. There are more than 10 alternatives to sSMTP for a variety of platforms, including Linux, Windows, Mac, BSD and Self-Hosted solutions. The best alternative is Postfix, which is both free and Open Source. Other great apps like sSMTP are OpenSMTPD (Free, Open Source), mailsend-go (Free, Open Source), Exim (Free, Open Source) and msmtp (Free, Open Source).