I run Courier IMAP with STARTTLS support. Currently, IMAP_TLS_REQUIRED is set to 0 (false), meaning that a client is fully permitted to use a clear-text login on an unsecured channel. Setting it to 1 (true) is not an option, as it breaks SquirrelMail (which can't use STARTTLS); however, I know for a fact that only certain IP addresses are legitimately going to be using unencrypted transport.

In the simplest case, it should theoretically be possible to permit connections from without encryption, while demanding STARTTLS before auth on all other connections. However, I've been unable to do this. Also, what if I want something more complicated - maybe there's a web server on talking to an IMAP server on, with a secure LAN in between. (Ignore for now the challenge of proving that the LAN truly is secure.) Is there a way to set IMAP_TLS_REQUIRED differently for different connections?

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.