issue2551350 - Python changes for 3.12 with roundup 2.3.0 mailer.py Fix due to change in smtplib.SMTP.starttls() signature. As of 3.3 it can use an optional ssl context argument for certificates/keys. In 3.12 it dropped legacy support for specifing cert/key files as arguments and requires a context. I modified Andrew's original patch to initialize SSLContext with ssl.PROTOCOL_TLS_CLIENT. If there is a cert file specified, enable check_hostname - verify that the cert supplied by the server matches the hostname we supplied. If there is no cert file call load_default_certs() Also opened issue2551351 to look into more SMTP ssmtp tightening. We also should have an option in Roundup to use TLS/SSL (smtps) without using starttls. Note that this code is untested by the test suite due to the need to setup an SMTP server with STARTTLS support. issue2551351 has some notes on this.

import operator

class MultiMapping:
    def __init__(self, *stores):
        self.stores = list(stores)
    def __getitem__(self, key):
        for store in self.stores:
            if key in store:
                return store[key]
        raise KeyError(key)
    _marker = []
    def get(self, key, default=_marker):
        for store in self.stores:
            if key in store:
                return store[key]
        if default is self._marker:
            raise KeyError(key)
        return default
    def __len__(self):
        return sum([len(x) for x in self.stores])
    def push(self, store):
        self.stores.append(store)
    def pop(self):
        return self.stores.pop()
    def items(self):
        l = []
        for store in self.stores:
            l = l + list(store.items())
        return l