We are trying to evaluate Mattermost for company messaging. I’ve setup and installed on Debian 8; everything is working fine except for email notifications. When I test the following I receive 2 errors:
TLS on 25: Failed to open TLS connection [details: tls: first record does not look like a TLS handshake]
STARTTLS on 587: Failed to authenticate on SMTP server [details: 504 5.7.4 Unrecognized authentication type]
The only way I’ve received successful test notifications via email is by using no encryption (PLAIN)
I did see how this was mentioned with regards to Office360 but we use an in-house Exchange 2013 server. Has anyone has luck getting this to work?.