ok, I got in touch with the email server and they said the email configuration should be PHP and not SMTP mailer. After they made the alteration that's when it all started to get the error.

They altered because I started having problems sending the mail to all the users at once. They said it was because I needed the PHP function to send mass email. So they altered the global configuration.

I'm sending the image attached.

Maybe I should go back to SMTP mailer, do you think it would solve the issue? I would rather have this to work fine than to send mass mail.

thanks

aiContactSafe is using Joomla's API to send emails. Not sure why that change in the configuration caused those problems. When you use the mass mail are the emails sent by it having the same problem or that has a sender email ?