On Thu, Mar 21, 2013 at 6:49 PM, Lindsay Haisley <fmouse-cour...@fmp.com> wrote: > Second, is Courier unique in exciting this particular config bug? > Surely many or most sending SMTP servers attempt to use STARTTLS if the > receiving server advertises support for it, and the mail admins of the > problem receiving Exchange server would doubtless become aware of such a > problem and fix it.
I don't know much about other servers, but Exim seems to handle this automagically. Exim's documentation has the following to say (http://www.exim.org/exim-html-current/doc/html/spec_html/ch-encrypted_smtp_connections_using_tlsssl.html#SECID185): "When the server host is not in hosts_require_tls, Exim may try to deliver the message unencrypted. It always does this if the response to STARTTLS is a 5xx code. For a temporary error code, or for a failure to negotiate a TLS session after a success response code, what happens is controlled by the tls_tempfail_tryclear option of the smtp transport. If it is false, delivery to this host is deferred, and other hosts (if available) are tried. If it is true, Exim attempts to deliver unencrypted after a 4xx response to STARTTLS, and if STARTTLS is accepted, but the subsequent TLS negotiation fails, Exim closes the current connection (because it is in an unknown state), opens a new one to the same host, and then tries the delivery unencrypted." Exim also provides a blacklist for bad hosts, so that you can do the same as Courier does. This seems like a very sane way to handle it, which would explain why we get so few complaints about lost mail to Exchange servers at $workplace, where we use Exim for authenticated outgoing SMTP. Doing it the Courier way ensures that there are fewer tries and retries for a given session to a misconfigured host, but IMHO, Courier developers might want to look into doing it similarly to Exim when there are no particular configuration options set for a given host. -- Jan ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar _______________________________________________ courier-users mailing list courier-users@lists.sourceforge.net Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
