I have a virtual server running on virtualmin with dovecot as IMAP and the only port open is 143.
I have let’s encrypt certificate and everything has been running fine on this server for email with Dovecot and Postfix

root@web:~# postconf mail_version
mail_version = 3.4.23

root@web:~# dovecot --version
2.3.4.1 (f79e8e7e4)

Debian Linux 10
Webmin version  2.111
Virtualmin version  7.10.0

I am using PHP 8.2 with brew on a macbook. I use the following start of script to connect to the server

$imap = imap_open('{domain.ca:143/tls}INBOX', 'username', 'password');

var_dump(imap_last_error());exit;

I keep getting a SSL negotiation failed regardless of /tls, /ssl or ssl/novalidate-cert. I have tried every combination and setting from the php manual. I have tried every solution on stack or online without any success.

It will only work if I do imap_open('{domain.ca:143/notls}INBOX', 'username', 'password');
Making this an unsecure connection. I would really like to know how I can make this a secure connection. What could I be doing wrong?

I also tried directly by the public IP. Postfix and dovecot are on domain.ca, not imap.domain.ca is that matters.

Warning: imap_open(): Couldn't open stream {domain.ca:143/tls}INBOX in /usr/local/var/www/index.php on line 5
string(58) "TLS/SSL failure for domain.ca: SSL negotiation failed"
Notice: PHP Request Shutdown: TLS/SSL failure for domain.ca: SSL negotiation failed (errflg=2) in Unknown on line 0

server journalctl says

ay 10 11:34:57 web.domain.ca dovecot[828]: imap-login: Disconnected (no auth attempts in 0 secs): user=<>, rip=x.x.x.x, lip=x.x.x.x, session=<qg0rRxsY/IVGNc6I>

so from what this log says, am I using this wrong? Should have have the auth. inside the ‘{domain.ca:143/notls}’ string? Or is this php extension configured not to check secure connect on 143?

Any help would be appriciated.

Thank you