Sending Emails fails with "Certificate for domain XXX is untrusted"

[Kinglui]

Hello,

i have some trouble sending emails and got an "Certificate for domain XXX is not trusted" message. So i can't send emails.

OS Version: CentOS Linux release 7.3.1611 (Core)
OX Version: open-xchange-7.8.4-6_6.1
SMTP Server: Postfix (startTLS)

com.openexchange.exception.OXException: SSL-0001 Categories=ERROR Message='The certificate for domain "XXXXXXXXX" is untrusted.' exceptionID=1388605030-40

I set the following ssl properties, without success.

com.openexchange.net.ssl.trustlevel=all
com.openexchange.net.ssl.whitelist=127.0.0.1-127.255.255.255,SMTPSERVER

Perhaps someon have an idea how i can accept untrusted certificates.

greets

Steffen