IMAP open stream: Self signed certificate issue

Question

I'm trying to open the non-secure (port 143) IMAP connection (I am using PHP):

imap_open('{localhost:143/imap}INBOX', USERNAME, PASS);

and I get the next error: Certificate failure for localhost: self signed certificate ...

Ok. I've tried to use /novalidate-cert mailbox param. Then I get another error: Can not authenticate to IMAP server.

I've also tried to combine all possible non-secure connection params like /notls,/norsh and /secure. But I always get errors.

This is the Dovecot configuration I'm using:

* OK [CAPABILITY IMAP4rev1 LITERAL+ SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH=LOGIN] Dovecot ready.

The certificate is really self-signed and generated with openssl.

The questions are:

1. Why does the certificate error occurs when I am using non-secure connection?
2. What is wrong with the mail server configuration?

Answer 1

Use this code

   imap_open('{localhost:143/imap/novalidate-cert/debug}INBOX', USERNAME, PASS);

Instead of this

    imap_open('{localhost:143/imap}INBOX', USERNAME, PASS); 

Answer 2

STARTTLS of course uses the certificate to start the TLS channel, hence why you saw a self-signed cert error. Can not authenticate, however, implies your username and password are wrong. Try logging in using telnet to verify your user and password are correct