I referred to this link
and my configuration looks like this:
# Email transport transport_email_enabled = true transport_email_hostname = smtp.google.com transport_email_port = 465 transport_email_use_auth = true transport_email_use_tls = false transport_email_use_ssl = true transport_email_auth_username = email@example.com transport_email_auth_password = 'Password' transport_email_subject_prefix = [graylog] #transport_email_from_email = firstname.lastname@example.org
SSL and TLS were not working together. So has to toggle one of them off (false).
I tried with a Less secure app On also with APP Password, still same facing the same issue.
I am not able to figure out the root of this issue if it is related to Gmail authentication or the gray server.
Tried both SSL and TLS on their respective ports (Port for SSL: 465 Port for TLS/STARTTLS: 587) same issue.
I have been trying it for more than a week now, no luck.
Any help would be appreciated.