Smtp configuration not working

use a exchange server without autentication. into the log i have
[twisted.mail.smtp.ESMTPSenderFactory#info] Starting factory <twisted.mail.smtp.ESMTPSenderFactory object at 0x7f6f82cc3470>
[stdout#info] [E] Unable to verify validity of certificate: <X509Name object ‘/CN=RUHDCPVEX01’>
[twisted.mail.smtp.ESMTPSenderFactory#info] Stopping factory <twisted.mail.smtp.ESMTPSenderFactory object at 0x7f6f82cc3470>
i add the certificate in ca with update ca debian procedure