How to fix No authentication mechanisms supported by both server and client error

Document ID : KB000118908
Last Modified Date : 02/11/2018
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Outgoing emails are not being sent out from CA Service Desk Manager (SDM) 17.1 setup.

mail_nxd.log show errors like this
2018-11-01 11:53:02:606 ERROR  [] c.c.S.m.NXJavaMailMailer - The transport is not connected or is dead.
javax.mail.AuthenticationFailedException: No authentication mechanisms supported by both server and client 
The error happens when SMTP server's authentication mechanism differs from the one that CA SDM is set with.
Here are some option combination to resolve the issue, based on how authentication is configured on the SMTP server:
SMTP Server Authentication / SDM optionsAuthentication is NOT requiredAuthentication IS RequiredAuthentication is NTLM
mail_login_userid & mail_login_passwordDeinstalledInstalledInstalled
mail_smtp_security_level01 or 42

A restart of mail_nxd or SDM is required after setting these options
Additional Information:
To verify if authentication is required or not, a test via telnet might be a good idea:

telnet <SMTPServer> <SMTP_PortNumber>    

It would indicate there normally if authentication is needed or not.  Below is a document from Microsoft that covers it in detail: