SMTP server for development on localhost written in python

gistfile1.txt

#!/usr/bin/env python

# This a simple smtp server for testing on localhost
# The original version is on https://coderwall.com/p/ufjgwa/smtp-server-on-python-for-development-with-storing-emails
# This version is more verbose on what is doing, with more parameters and fail safe checks.

import argparse
import asyncore
import smtpd
import time
import os

 
SMTPD_MAIN_CLASSES = [
    smtpd.DebuggingServer.__name__,
    smtpd.PureProxy.__name__,
    smtpd.MailmanProxy.__name__,
]
 
 
def storeproxy_factory(base_class, store_path, verbose):
    class StoreProxy(base_class):
 
        def process_message(self, peer, mailfrom, rcpttos, data):
            filename = '%d_%s.eml' % (int(time.time()), '_'.join(rcpttos))
            with open(os.path.join(store_path, filename), 'w') as f:
                f.write(data)

            if verbose:
                print data
 
    return StoreProxy
 
def get_argparser():
    parser = argparse.ArgumentParser(description='Development SMTPd')
    parser.add_argument(
        '-c',
        '--class',
        choices=SMTPD_MAIN_CLASSES,
        default=SMTPD_MAIN_CLASSES[0],
        type=str,
        dest='klass'
    )
    parser.add_argument(
        '-l',
        '--localaddr',
        nargs=1,
        default='127.0.0.1:1025',
        type=str
    )
    parser.add_argument(
        '-r',
        '--remoteaddr',
        nargs=1,
        default='127.0.0.1:2525',
        type=str
    )
    parser.add_argument(
        '-s',
        '--store',
        nargs=1,
        type=str
    )
    parser.add_argument(
        '-v',
        '--verbose',
        action='store_true'
    )
 
    return parser
 
def normalize_addr(addr):
    if isinstance(addr, list):
        addr = addr[0]
    if ':' in addr:
        host, port = addr.split(':')
        return (host, int(port))
    return None
 
def main():
    args = get_argparser().parse_args()
 
    server_class = getattr(smtpd, args.klass)
    if args.store:
        if not os.path.isdir(args.store[0]):
            raise AttributeError("The file specified does not exists or is not a folder")
        print "Storing in folder:", args.store[0]
        server_class = storeproxy_factory(server_class, args.store[0], args.verbose)
 
    server = server_class(
        normalize_addr(args.localaddr),
        normalize_addr(args.remoteaddr)
    )

    print "Server:", server_class
    print "Address:", args.localaddr
    print "Remote address:", args.remoteaddr
    print "Verbose:", args.verbose

    try:
        asyncore.loop()
    except KeyboardInterrupt:
        server.close()
 
if __name__ == '__main__':
    main()