Unable to send mail using PHPMailer using SMTP on another box

[k1l0b1t]

Hello

When using SMTPMailer in PHP, I'm able to use my local SMTP server, but not the SMTP server my clients domain uses.
When I try to connect, I get connection refused errors.

The client reports their mailserver fails on DN="/ CN=<hostname.domain.com>" H="<mail.domain.com>".

This is verry odd, since the SMTP credentials don't use domain.com at all.
Anyone an idea what causes this?

Thanks
PS: also can't telnet to that mail system somehow. I can from a difirent machine (not running any mailservers itself)

 

[zEitEr]

Hello,

A remote host might use a single certificate for SMTP, and doesn't support SNI. If this is the case, then it's expected.

I believe you might check documentation for SMTPMailer and use an option to ignore SSL hostname mismatch.

And what error do you get when trying?

telnet mail.domain.com 25