Etherpad email fails with javax.mail.MessagingException: 501 Syntax: HELO hostname

Output from bin/run.sh &

Try to register for a pro account and you get

javax.mail.MessagingException: 501 Syntax: HELO hostname

at com.sun.mail.smtp.SMTPTransport.issueCommand(SMTPTransport.java:1363)
at com.sun.mail.smtp.SMTPTransport.helo(SMTPTransport.java:838)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:375)
at javax.mail.Service.connect(Service.java:275)
at javax.mail.Service.connect(Service.java:156)

Cause: Hostname isn’t in /etc/hosts

Solution:

hostname

Copy hostname value and paste to /etc/hosts