31 Aug
2020
31 Aug
'20
8:46 p.m.
You don't mention where your mailserver is. There are likely some locations where you'll never be able to send mail reliably. I don't have a specific tutorial to point you to, but I think conventional wisdom says: - need forward and reverse DNS that match - using TLS will help - having SPF records on your domain will help - using DKIM will help SPF and DKIM are easily google-able. The rumour is that some recipients (e.g. gmail) are more particular about inbound mail that arrives over IPv6. Any chance you have another mail service with good reputation that you could use as an outbound mail relay? It's fairly easy with postfix to arrange to send all outbound mail through some other (authenticated) SMTP server. Hope that helps! John