Question about sending emails from gmail smtp

Hello guys, im trying to send cold emails with gmail smtp under my domain name, however they are going to “promotions” tab.

If i send without a gmail smpt, with my normal gmail name, then all good , but once i send it through gmail smpt with @mydomain all emails go to “promotions” tab.

I tried serveral domains, so its not domain issue. Maybe anyone know how to hit inbox while sending mails from your business domain email address?

You need to properly warm up your domain.

But on gsuite, once i create it and send emails, all emails go to inbox, without even warming it up. So im thinking why on gsuite all good , but on a normal gmail with a business email it goes to promotional…