The exception that you are receiving "No login methods supported!" is indicating that the email server has not been configured to allow PRPC application to send emails using the username / password that prpc is using
Has the username used when you ran the email server wizard been tested to see if it can send emails?
"No login methods supported" means that the login methods (not the specific credentials) provided by the server did not intersect with those that Pega (Java Mail) was told to support for the connection.
There are multiple possible casues. Some that come to mind are:
The client is not using SSL or STARTTLS but the server requires it. This happens often when the client is coming from outside the corporate network.
The version of Java Mail in use by Pega is "old" and does not support the authentication method that the server requries.
client's IP or domain is impacting the security policies on the server
There is a load balancer that is causing requests from the client to go to a wrong or badly configured email relay/server
The hosts file or DNS cache is causing the client to connect to the wrong relay/server
We're using Microsoft Exchange server. I've now raised an SR (SR-B183) for this and it looks like there needs to be a fix done on Pega side. We did a test run of modifying POP3orIMAPConnectivity activity. After doing that change, doing a test connectivity on the email receiver connected successfully to the email server.