gnus: POP before SMTP

 
 5.3 POP before SMTP
 ===================
 
 Does your ISP use POP-before-SMTP authentication?  This authentication
 method simply requires you to contact the POP server before sending
 email.  To do that, put the following lines in your ‘~/.gnus.el’ file:
 
      (add-hook 'message-send-mail-hook 'mail-source-touch-pop)
 
 The ‘mail-source-touch-pop’ function does POP authentication according
 to the value of ‘mail-sources’ without fetching mails, just before
 sending a mail.  SeeMail Sources.
 
    If you have two or more POP mail servers set in ‘mail-sources’, you
 may want to specify one of them to ‘mail-source-primary-source’ as the
 POP mail server to be used for the POP-before-SMTP authentication.  If
 it is your primary POP mail server (i.e., you are fetching mails mainly
 from that server), you can set it permanently as follows:
 
      (setq mail-source-primary-source
            '(pop :server "pop3.mail.server"
                  :password "secret"))
 
 Otherwise, bind it dynamically only when performing the POP-before-SMTP
 authentication as follows:
 
      (add-hook 'message-send-mail-hook
                (lambda ()
                  (let ((mail-source-primary-source
                         '(pop :server "pop3.mail.server"
                               :password "secret")))
                    (mail-source-touch-pop))))