Scenario – You are using a mail adapter in SAP CPI artifact / iflow and getting below error.

Error – javax.mail.AuthenticationFailedException: No authentication mechanisms supported by both server and client.

Cause – You are not using the correct authentication mechanism in Mail adapter -> Connection – > Authentication 

You have used the incorrect combination in Mail Adapter ex. Encrypted User name and password. But, you are providing a plain user name and passowrd.

Resolution – If you are using a plain user name and password combination, that you have stored in Key Store. Change the Authentication to Plain User / Password. Save it and deploy again. 

Result – Now the error “javax.mail.AuthenticationFailedException: No authentication mechanisms supported by both server and client” is gone. There might be another authentication combinations other than above which can cause this error. Choose the correct one.

Check out SAP CPI Mail adapter details from SAP Help. Learn more from other blogs.