SMTP RCPT TO Invalid address

PROBLEM:
Recently when my web application was sending out SMTP emails out to end users, I noticed the following error-
javax.mail.SendFailedException: Invalid Addresses;
com.sun.mail.smtp.SMTPAddressFailedException: 501 5.1.3 Invalid address
at com.sun.mail.smtp.SMTPTransport.rcptTo(SMTPTransport.java:1196)

CAUSE:
The end user's email address was not correct i.e., instead of being in the format of "user@domain.com", it was formatted as "user" i.e., missing domain information.

IBM WAS Changing Class Loader Policy on the Fly

I was recently working with an application and I needed to change the Class Loader policy for the WAS 7.0 server. It was set to "SINGLE". There was an issue with Integrated Service Console (ISC) application which also happens to be the Admin Console for the local installation. I could not bring up the Admin Console.

I discovered that I could change the classloader policy at the Server level from "SINGLE" to "MULTIPLE" by (a) opening this file using a text editor -C:\WAS70\profiles\AppSrv01\config\cells\US-L3L5666-LNode02Cell\nodes\US-L3L5666-LNode02\servers\server1\server.xml
(b) replace "SINGLE" with "MULTIPLE"