ZoneMTA is an opensource Nodejs and MongoDB based mail transfer agent which offers you enterprise level MTA (mail transfer agent) features to send bulk emails.
It offers a wide range of features and functionality which makes it out of the box opensource MTA compare to other opensource MTA software like Postfix, iRedmail, Exim etc.
Most significant features of ZoneMTA:
Fast Processing: ZoneMTA run on top of fastest server platform Nodejs and uses NoSQL database MongoDB, It can send millions of emails in a day.
Multi IP Rotation: ZoneMTA offers you multiple IP rotation features which is one of the key features in commercial MTA like MailerQ, GreenArrow, and PowerMTA etc. you can one or more IPs to send emails from different IPs in batch.
IP Warmup: ZoneMTA gives you feature to control the reputation of your IP you can assign different email volume to be rendered through different sending IP.
DKIM Support: DomainKeys Identified Mail is one of the authentication protocol to be used while sending bulk emails and ZoneMTA does offer you to add DKIM signature in your sending domain.
ZoneMTA still in beta version but it is already being used in production server.