Mail cannot be send to a particular domain. There is error: "TLS connect failed".
Hi. This is the qmail-send program at mail.domain.tld.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.
TLS connect failed; connected to 192.168.1.1.
I'm not going to try again; this message has been in the queue too long.
Qmail uses TLS (SSL connection) to send mail. If destination SMTP server doesn't support TLS, you get the error listed above. You can test if the server supports TLS with:
# telnet 192.168.1.2 25
Connected to 192.168.1.1.
Escape character is '^]'.
220 mail.domain.tld ESMTP
250-AUTH=LOGIN CRAM-MD5 PLAIN
250-AUTH LOGIN CRAM-MD5 PLAIN
250-STARTTLS line means that TLS connection is supported.