CnMaestro OnPremises - eMail sending error

Hi, wev just downloaded and installed a on premises image and after all we can not configure e'mail sending in Settings Page.. We get a PROTOCOL ERROR when sending and after putting in debug mode , this showed in logs (same as error appear in cnmaestro UI):

Error on sending mail: 140278538590016:error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol:../deps/openssl/openssl/ssl/s23_clnt.c:827:

Tested dns resolution against them and another smtp provider but same error.

Are you using GMAIL server for SMTP?