Caldera Forms emails failing

when someone send a message tru the form, this error returns in wp mail smtp:

Email Source: Caldera Forms
Mailer: Padr?o (nenhum)
PHPMailer was able to connect to SMTP server but failed while trying to send an email.
For more details please try running an Email Test or reading the latest error event.`

when i send a test email its working fine, something is happening between caldera and smtp, can someone help? is it happening to someone else?

thanks in advance