Emails from registrants comes from our own email address, should not be the case

Hi,  Our link below is a registration link for our event. When teams register it actually shows it coming from us. see image below as well

I have checked your form and noticed you have configured custom SMTP such that when user fill notification the autoresponse email is sent to user email through your mail server hence responses would be going to your user from your email server.

If I may ask do you want to change this to be email for instance from "noreply@jotfrom.com"? This is based on your thread title where you have stated "Emails from registrants comes from our own email address, should not be the case " if you need to change this to either "norepy@jotform.com" or "noreply@formresponse.com"  follow the guide below. When you reach step 4 choose any of the Jotform sender mails above. You will not need to proceed to the next steps other than save.

https://www.jotform.com/help/238-How-to-Add-a-Custom-Sender-Address-to-an-Email-Alert

On the issue of the error image you have shared, since this mail is originating from your servers you may need to confirm with your email provider as to why you are getting the response since all he configurations on your email settings are OK the only explanation would be some configuration on your mail server is missing hence getting the error.