Guide to Spring Email | Baeldung
https://www.baeldung.com/spring-email15.01.2017 · Some SMTP servers require a TLS connection, so we use the property spring.mail.properties.mail.smtp.starttls.enable to enable a TLS-protected connection. 3.2.1. Gmail SMTP Properties We can send an email via Gmail SMTP server. Have a look at the documentation to see the Gmail outgoing mail SMTP server properties.