Outgoing Email issue on Galaxy S4 phone

[#1]

For the last 2 days I have been unable to send emails from my galaxy S4 phone.  I get the following message "server password has been changed.  Input the changed password" please can someone help me

[#2]

Whose network are you connected to when trying to send mail? I can't see anything obvious wrong with your account. If you're using port 25, try 587 (or vice versa). Make sure you're using relay.plus.net as the outbound server, have SSL disabled and double check the username and password you're using to send mail with (can you log into webmail using the same details?)