I have found we can send outbound email in Alfresco via Google's SMTP server (smtp.gmail.com). According to Google 's SMTP server uses TTLS encryption, it is a matter of configuring the JavaMail to use TTLS. Alfresco version: 3.4.4 EE, 4.0.x EE and Community. Step 1. modifying ${ALFRESCO_HOME}/tomcat/shared/classes/alfresco-global.properties as below.
mail.host=smtp.gmail.com mail.port=465 mail.username= mail.password= mail.protocol=smtps mail.from.default=alf_admin@your.com mail.encoding=UTF-8 mail.smtps.auth=true mail.smtps.starttls.enable=true
Step 2. Enable the Spring JavaMail bean for TLS (only necessary for 3.4) Please add the "mail.smtp.starttls.enable" line as below. ${ALFRESCO_HOME}/tomcat/shared/classes/alfresco/subsystems/email/OutboundSMTP/outboundSMTP-context.xml
${mail.host}
${mail.port}
${mail.protocol}
${mail.username}
${mail.password}
${mail.encoding}
${mail.smtp.auth}
${mail.smtp.starttls.enable}
Step 3. restart Alfresco server.