Do not try to host outbound mail on residential IP blocks, delivery will be really bad. Cheap VPS is same story. You best bet is VPS from some not well know provider, they may be avoid to be in blacklist in M$ and Google. Inbound mail is fine anywhere as so long as you can have port 25 open. DDNS works too.

Hosting email with mailcow dockerized worked pretty good on my netcup vps, but before you go into hosting email ask yourself a few questions:

• Will you use your selfhosted mail for important things? (Banking, official correspondence and so on)
• Can you promise a near 100% uptime? Otherwise, some email might not reach you.
• How important is the Mail you send? Some (stupid) Blocklists generally block all IP ranges that are sold out by vps companies and other kinds of IAAS.
• If you register any accounts with your selfhosted mail, can you guarantee yourself that your email account is secure? Don’t underestimate what an attacker can do with a compromised Mail account.

I personally ended up scrapping my email server eventually. Nowadays I pay a company to do the mail hosting, you just need to set some DNS records and they do everything else. Personally, I’m with proton, but there are many good alternatives.

You can selfhost the email server wherever you want. But you’ve to use some external system to deliver the email or you’ll end up in spam because your residential IP is most likely dynamic and already flagged by most email providers.

One way to do it is to get a VPS somewhere and setup Wireguard on it. Then configure your local system to bind to the Wireguard interface and IP so all email send and received using the tunnel. Dovecot doesn’t care what interface it is running on, Postfix has specific options that you can change in master.cf to accommodate the fact that it will be binding to the VPN IP and the real IP is the VPS public IP.

1. Setup a install of Dovecot / Postfix / Rspamd on your local server: https://workaround.org/ispmail-bookworm/
2. Start by setting up a Wireguard tunnel between your local server and the VPS: https://www.digitalocean.com/community/tutorials/how-to-set-up-wireguard-on-ubuntu-20-04
3. Create a outgoing transport for the email that uses the WG tunnel and is aware of the VPS public IP:

out-wg      unix  -       -       n       -       -       smtp
 -o proxy_interfaces=188.xxx.xxx.xxx # the real public IP of the VPS
 -o smtp_bind_address=10.0.0.2 # the IP that your local server has on the WG interface
 -o inet_interfaces=10.0.0.2 # same as above
 -o myhostname=server.example.org # should match the PTR / reverse DNS entry on the VPS IP
 -o smtp_helo_name=server.example.org # should match the PTR / reverse DNS entry on the VPS IP
 -o syslog_name=smtp-wg

4. Set your VPS firewall to NAT/forward incoming traffic on port 25, 587, 465 and 993 to the local server (wireguard client 10.0.0.2);
5. Change main.cf to use the transport by adding: default_transport = out-wg.

That’s everything you need to get it going. Use https://www.mail-tester.com/ to debug if DKIM and everything else is properly setup at the end.

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I’ve seen in this thread:

9 acronyms in this thread; the most compressed thread commented on today has 9 acronyms.

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