Encrypting password for email

[msalguer]

I try OpenPop method with gmail account and appears this error:
Server did not accept user credentials
en OpenPop.Pop3.Pop3Client.Authenticate(String username, String password, AuthenticationMethod authenticationMethod)
en Email.FetchAllMessages(String hostname, Int32 port, Boolean useSsl, String username, String password)
en Email.Receive(String server, Int32 port, Boolean useSsl, String user, String password).

Sorry, I'm not able to do :-(
Maybe just the IMAP option for Gmail accounts / Yahoo. I try...
I will prove if POP3 method works with a own domain email account ...