Mailkit.Security.AuthenticationException: Unable to send mail using Smtp mail activity

Hi ,
I am using smtp mail activity to send mail we are using Imail server and port no is 25
server name and port no is correct and working even Username and Password is also correct still getting Authentication Failed error
“Error:authentication failed:UGFzc3dvcmQ6”
Exception Type:Mailkit.Security.AuthenticationException

Smtp detials:

Can you change SecureConneciton Value and try

message 535: 5.7.8 Error: authentication
This message is credentials is not correct, may be the username or password is not correct

@Eric_Wong_Test User id and Password is correct

@Mr.StarLord_AO Tried changing secureConnection still getting same error

Are yo using gmail?

No,I am using Orgainization Email id

Please check your LAN settings in IE
Also Usually an outgoing server employs port 25 : it’s the default SMTP port . However, some IPs deny its use because of the massive spam and malware traffic by which is affected. This issue is raised in particular when you need to switch to another ISP – for instance, when you’re travelling and connecting to a new provider. In this case you can try to use port 587 or port 465 to avoid the block.