[Mail signature error]

The ESET Mail Security, ESET File Security, when sending the mail places a signature that causes an alteration in the mail, specifically in the DKIM.
It reads what gmail indicates and recommends the following:
*) configure the gateway so that it does not change outgoing messages.
*) Configure the gateway to change the message first and then add the signature with DKIM.
I want to know how I could deactivate the signature to solve this problem since my emails are taken as SPAM