Use your domain, not gmail
Send from you@yourbusiness.co.za, not a free @gmail.com. It looks professional and lets you authenticate properly.
A domain address isn't just tidier — it's the only way you can actually set up SPF, DKIM and DMARC.
Set the three records
Ask your email provider for their SPF, DKIM and DMARC settings and add them to your DNS. Even a p=none DMARC starts the clock on visibility. (Prefer we set it up? We do this for a fixed fee.)