I hope this might help others as we spent hours trying to figure this out..
First, signup with mailersend, they have a great free package and they are a lot cheaper than Mailgun as Mailgun don't do any free or customized packages for low volumes of 5000 email per month or less.
Configure mailersend SMTP and verify your domain then add this on .env folder MAIL_FROM_VERIFIED_EMAIL=true then follow AQSharif link recommendation and it works it's magic.
However we're not able to be able to send the emails from the tenant email address, but the name switches from your company to the tenant, which is a lot better.
I just really really wish the dev team add SMTP configuration for tenants as an additional option if the tenant wants to use it or not