External email warning when sent to contacts in our own domain

When sending an email broadcast from a user/owner from our company email domain to our team members also in our company email domain we are getting an external banner warning that the email is being sent from outside our domain.

So the email ‘appears’ to be sent from @companyname.com and recipients are all members of the @companyname.com domain. So is there something in the email header/metadata somewhere that makes it appear to be an externally generated email (which I guess it is) when it is being sent from and to members of our company domain.

I need guidance on any specific fields causing this so I can approach out IT provider to get them to fix it.

Thanks in anticipation of your help!

The emails are sent from ‘infusion mail’, so they are not being sent from your domain directly.

Make sure you have your DKIM settings configured properly.

Typically, you see this when the DKIM is not set up properly, so your email system sees the email as sent from “infusionmail” and there is nothing in the SPF or DKIM records to tell your email system that ‘infusion mail’ is an authorized sender on your behalf.