ocemail.js

var ocemail = function(url, domain) {
    var capitalize = function(s) { return s.charAt(0).toUpperCase() + s.slice(1).toLowerCase(); }

    // url parser from http://jsperf.com/url-parsing
    var urlParseRE = /^(((([^:\/#\?]+:)?(?:(\/\/)((?:(([^:@\/#\?]+)(?:\:([^:@\/#\?]+))?)@)?(([^:\/#\?\]\[]+|\[[^\/\]@#?]+\])(?:\:([0-9]+))?))?)?)?((\/?(?:[^\/\?#]+\/+)*)([^\?#]*)))?(\?[^#]+)?)(#.*)?/;
    var hostname = urlParseRE.exec(url)[11];

    if (hostname) {
        var domainMatch = /^(?:www[.])?([-a-z0-9]+)[.](house|senate)[.]gov$/;
        var match = domainMatch.exec(hostname.toLowerCase());
        
        var nameish = match[1],
            chamber = match[2];

        var prefix = chamber == 'senate' ? 'Sen' : 'Rep';
        return [capitalize(prefix), ".", capitalize(nameish), "@", domain ? domain : "opencongress.org"].join("");
    }
}

ocemail.py

import re
try:
  from urlparse import urlparse # python 2
except:
  from urllib.parse import urlparse # python 3

def ocemail(url, domain='opencongress.org'):
  parts = urlparse(url)
  if parts.hostname:
    match = re.match(r'^(?:www[.])?([-a-z0-9]+)[.](house|senate)[.]gov$', parts.hostname.lower(), re.I)
    nameish, chamber = match.groups()
    prefix = 'Sen' if chamber == 'senate' else 'Rep'
    return "%s.%s@%s" % (prefix.capitalize(), nameish.capitalize(), domain)

ocemail.rb

def ocemail (website)
  pattern = /^(?:www[.])?([-a-z0-9]+)[.](house|senate)[.]gov$/i
  url = URI.parse(website)
  return nil if url.host.nil?
  match = pattern.match(url.host.downcase)
  return nil if match.nil?
  nameish, chamber = match.captures
  prefix = (chamber.downcase == 'senate') ? 'Sen' : 'Rep'
  return "#{prefix.capitalize}.#{nameish.capitalize}@#{Settings.email_congress_domain}"
end