docs: def send_welcome_message(self, user, base_url):
          """ Send welcome mail with email confirmation link """
          if not self.require_confirmation and not self.welcome_message:
              return
  
          # get subject
          subject = ''
          subjects = self.email_subjects
          if self.require_confirmation:
              subject = 'Welcome, please activate your account!'
              if 'welcome_confirm' in subjects.keys():
                  subject = subjects['welcome_confirm']
          if not self.require_confirmation:
              subject = 'Welcome to our site!'
              if 'welcome' in subjects.keys():
                  subject = subjects['welcome']
  
          # prepare data
          sender = current_app.config['MAIL_DEFAULT_SENDER']
          recipient = user.email
          link = '{url}/{link}/'.format(
              url=base_url.rstrip('/'),
              link=user.email_link
          )
          data = dict(link=link)
  
          # render message
          if self.require_confirmation:
              html = render_template('user/mail/account-confirm.html', **data)
              txt = render_template('user/mail/account-confirm.txt', **data)
          else:
              html = render_template('user/mail/welcome.html', **data)
              txt = render_template('user/mail/welcome.txt', **data)
  
          # and send
          mail.send(Message(
              subject=subject,
              recipients=[recipient],
              body=txt,
              html=html,
              sender=sender
          ))