I'm just thinking out loud here and wondered if i have to open up ports (inbound) to still use my mail.
Isn't it possible to redirect trafic lets say imap or pop3 through a subdomain (imap.domain.tld or pop3.domain.tld) hosted at port 80 or 443 and then redirect it with nginx through a proxy_pass
?
If this is not the way to go i'm wondering why the big guys like google and such all have a seperate subdomain for all these protocols...
If possible i'd love to tighten up my vps as much as possible but still keeping the neccesairy things..