SMTP (Simple Mail Transfer Protocol) is a protocol created for communication. It sends emails over the Web. SMTP plugin is a great solution to configure and send emails using mail services such as Hotmail, Gmail and Yahoo as well as mail gateways (e.g. Mailjet). It will prevent your messages from getting into the spam/junk folder of your recipients.
SMTP plugin allows you to securely deliver emails to your recipients as well as to configure the sending email messages with the help of mail gateways and main email services. This plugin provides an easy way of sending test emails, which makes the configuration process much easier and you will not have to deal with a bunch of settings.