This worked for me in Windows server
# SMTP settings
grails.mail.default.from=j****@****.com
grails.mail.host=
smtp.office365.comgrails.mail.port=587
grails.mail.username=
j****@****.com
grails.mail.password=*********
#grails.mail.props=["mail.smtp.auth":"true","mail.smtp.starttls.enable":"true"]
grails.mail.props.mail.smtp.starttls.enable=true
grails.mail.props.mail.smtp.auth=true