I'm surprised that someone is having problem sending email to gmail from their own smtp server. I am doing this for years with tens of thousands emails delivered every week (sometimes daily), yet had no issues. Here are few advises:
- ensure your external IP reputation is good. Check blacklists.
- configure correct dns/reverse dns (PTR) records.
- setup SPF (maybe DKIM with DMARC but I'm not using these)
- ensure your external IP reputation is good. Check blacklists.
- configure correct dns/reverse dns (PTR) records.
- setup SPF (maybe DKIM with DMARC but I'm not using these)
- do not spam.
Thats it.