Yes, once again Google has updated their GMail SSL certificate again causing possible errors with MAILTOOL and MAILTOOL Plus returning RC(-23). This error means "I don't trust the Certificate Authorities that signed the SSL certificate.".
MAILTOOL was updated a while back so that strict SSL could be turned off. Please see this article on how to turn off Strict SSL with MAILTOOL to avoid this error:
If your version of MAILTOOL does not have this data area, you will need to download and install the latest version. Don't forget to email us with the information from the DSPMCHINF command on each partition you are updating so we can send you updated license keys as well.