[Mashiro]

Sending and receiving e-mails from a mail server on a NAT VPS? WOW. That's a funny idea and rather not so professional and absolutely not recommended.

- Check the reputation of the IP address
- is the rDNS record correct
- SPF and DKIM configured (and configured correctly)?

If all above is OK you are most likely simply in Googles internal blacklist and you won't get off it so easy.


For your second problem: to send e-mails you generally need POP/IMAP and for receiving you need SMTP. So check if your SMTP server is setup correctly and running properly to accept mails.


Anyway... STOP RUNNING A MAIL SERVER ON A NAT VPS.