add mail server guide
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Robin Raymond
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README.md
247
README.md
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@ -53,7 +53,7 @@ None so far.
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* rename domain to fqdn, seperate fqdn from domains
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* rename domain to fqdn, seperate fqdn from domains
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* multi domain support
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* multi domain support
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### How to Deploy
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### Quick Start
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```nix
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```nix
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{ config, pkgs, ... }:
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{ config, pkgs, ... }:
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@ -88,7 +88,204 @@ None so far.
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For a complete list of options, see `default.nix`.
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For a complete list of options, see `default.nix`.
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### How to Test
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## How to Set Up a 10/10 Mail Server Guide
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Mail servers can be a tricky thing to set up. This guide is supposed to run you
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through the most important steps to achieve a 10/10 score on `mail-tester.com`.
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What you need:
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* A server with a public IP (referred to as `server-IP`)
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* A Fully Qualified Domain Name (`FQDN`) where your server is reachable. Note
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so that other servers can find yours. Common FQDN include `mx.example.com`
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(where `example.com` is a domain you own) or `mail.example.com`. The domain
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is referred to as `server-domain` (`example.com` in the above example) and
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the `FQDN` is referred to by `server-FQDN` (`mx.example.com` above).
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* A list of domains you want to your email server to serve. (Note that this
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does not have to include `server-domain`, but may of course). These will be
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referred to as `domains`. As an example, `domains = [ example1.com,
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example2.com ]`.
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### A) Setup server
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The following describes a server setup that is fairly complete. Even though
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there are more possible options (see `default.nix`), these should be the most
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common ones.
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```nix
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{ config, pkgs, ... }:
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{
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imports = [
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(builtins.fetchTarball "https://github.com/r-raymond/nixos-mailserver/releases/tag/v2.0-rc1")
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];
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mailserver = {
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enable = true;
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fqdn = <server-FQDN>;
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domains = [ <domains> ];
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# A list of all login accounts. To create the password hashes, use
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# mkpasswd -m sha-512 "super secret password"
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loginAccounts = {
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"user1@example.com" = {
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hashedPassword = "$6$/z4n8AQl6K$kiOkBTWlZfBd7PvF5GsJ8PmPgdZsFGN1jPGZufxxr60PoR0oUsrvzm2oQiflyz5ir9fFJ.d/zKm/NgLXNUsNX/";
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};
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"user2@example.com" = { ... };
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};
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# Virtual aliases. These are email addresses that are forwarded to
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# loginAccounts addresses.
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virtualAliases = {
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# address = forward address;
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"info@example.com" = "user1@example.com";
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"postmaster@example.com" = "user1@example.com";
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"abuse@example.com" = "user1@example.com";
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"user1@example2.com" = "user1@example.com";
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};
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};
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# User Let's Encrypt certificates
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certificateScheme = 3;
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# Enable IMAP and POP3
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enableImap = true;
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enablePop3 = true;
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enableImapSsl = true;
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enablePop3Ssl = true;
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# whether to scan inbound emails for viruses (note that this requires at least
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# 1 Gb RAM for the server. Without virus scanning 256 MB RAM should be plenty)
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virusScanning = false;
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}
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```
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After a `nixos-rebuild switch --upgrade` your sever should be good to go. If
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you want to use `nixops` to deploy the server, look in the subfolder `nixops`
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for some inspiration.
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### B) Setup everything else
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#### Step 1: Set DNS entry for server
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Add a DNS record to the domain `server-domain` with the following entries
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| `server-FQDN` | 10800 | A | | `server-IP` |
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This resolved DNS equries for `server-FQDN` to `server-IP`. You can test if your
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setting is correct by
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```
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ping <server-FQDN>
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64 bytes from <server-FQDN> (<server-IP>): icmp_seq=1 ttl=46 time=21.3 ms
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...
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```
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Note that it can take a while until a DNS entry is propagated.
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#### Step 2: Set rDNS (reverse DNS) entry for server
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Wherever you have rented your server, you should be able to set reverse DNS
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entries for the IP's you own. Add an entry resolving `server-IP` to
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`server-FQDN`
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You can test if your setting is correct by
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```
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host <server-IP>
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<server-IP>.in-addr.arpa domain name pointer <server-FQDN>.
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```
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Note that it can take a while until a DNS entry is propagated.
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#### Step 3: Set `MX` Records
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For all `domain` in `domains` do:
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* Add a `MX` record to the domain `domain`
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| `domain` | | MX | 10 | `server-FQDN` |
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You can test this via
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```
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dig -t TXT <domain>
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...
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;; ANSWER SECTION:
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<domain> 10800 IN MX 10 <server-FQDN>
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...
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```
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Note that it can take a while until a DNS entry is propagated.
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#### Step 4: Set `SPF` Records
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For all `domain` in `domains` do:
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* Add a `SPF` record to the domain `domain`
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| `domain` | 10800 | TXT | | `v=spf1 ip4:<server-IP> -all` |
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You can check this with `dig -t TXT <domain>` similar to the last section.
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Note that it can take a while until a DNS entry is propagated. If you want to
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use multiple servers for your email handling, don't forget to add all server
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IP's to this list.
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#### Step 5: Set `DKIM` signature
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For all `domain` in `domains` do:
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* Go to your server and navigate to the dkim key directory (by default
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`/var/dkim`. There you will find a public key for any domain in the
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`domain.txt` file. It will look like
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```
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mail._domainkey IN TXT "v=DKIM1; r=postmaster; g=*; k=rsa; p=<really-long-key>" ; ----- DKIM default for domain.tld
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```
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* Add a `DKIM` record to the domain `domain`
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| mail._domainkey.`domain` | 10800 | TXT | | `v=DKIM1; p=<really-long-key>` |
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You can check this with `dig -t TXT <domain>` similar to the last section.
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Note that it can take a while until a DNS entry is propagated.
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### C) Test your Setup
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Write an email to your aunt (who has been waiting for your reply far too long),
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and sign up for some of the finest newsletters the Internet has.
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Besides that, you can send an email to `mail-tester.com` and see how you score,
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and let `http://mxtoolbox.com/` take a look at your setup, but if you followed
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the steps closely then everything should be awesome!
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## How to Backup
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This is really easy. First off you should have a backup of your
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`configuration.nix` file where you have the server config (but that is already
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in a git repository right?)
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Next you need to backup `/var/vmail` or whatever you have specified for the
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option `mailDirectory`. This is where all the mails reside. Good options are a
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cron job with `rsync` or `scp`. But really anything works, as it is simply a
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folder with plenty of files in it. If your backup solution does not preserve the
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owner of the files don't forget to `chown` them to `virtualMail:virtualMail` if you copy
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them back (or whatever you specified as `vmailUserName`, and `vmailGoupName`).
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Finally you can (optionally) make a backup of `/var/dkim` (or whatever you
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specified as `dkimKeyDirectory`). If you should lose those don't worry, new ones
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will be created on the fly. But you will need to repeat step `B)5` and correct
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all the `dkim` keys.
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## How to Test for Development
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You can test the setup via `nixops`. After installation, do
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You can test the setup via `nixops`. After installation, do
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@ -111,52 +308,6 @@ openssl s_client -host mail.example.com -port 143 -starttls imap
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```
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```
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## How to Set Up a 10/10 Mail Server
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Mail servers can be a tricky thing to set up. This guide is supposed to run you
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through the most important steps to achieve a 10/10 score on `mail-tester.com`.
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### Fully Qualified Domain Name
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No matter how many domains you want to serve on your mail server, you need to
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settle on a _Fully Qualified Domain Name_ (FQDN) where your server is reachable,
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so that other servers can find yours. Common FQDN include `mx.example.com`
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(where `example.com` is a domain you own) or `mail.example.com`.
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After you settled on a FQDN (we will assume `mx.example.com` henceforth) you
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need to
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* Set a DNS entry on your domain to point to the IP of the server. For this
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add a DNS record such as
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| mx.example.com | 10800 | A | | `xxx.xxx.xxx.xxx` |
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to your domain, where `xxx.xxx.xxx.xxx` is the IP of your server.
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* Set a `rDNS` (reverse DNS) entry for your FQDN. You need to do so wherever
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you have rented your server. Make sure that `xxx.xxx.xxx.xxx` resolves to
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`mx.example.com`.
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### MX Record
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| domain1.com | | MX | 10 | mx.exmaple.com |
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### Spf record
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| domain1.com | 10800 | TXT | | `v=spf1 ip4:xxx.xxx.xxx.xxx -all` |
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### DKIM signature
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| Name (Subdomain) | TTL | Type | Priority | Value |
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| ---------------- | ----- | ---- | -------- | ----------------- |
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| dkim._domainkey.domain1.com | 10800 | TXT | | `v=DKIM1; p=yyyyyyyyyyyy` |
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where `yyyyyyyyyyyy` is the `DKIM` signature
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## A Complete Mail Server Without Moving Parts
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## A Complete Mail Server Without Moving Parts
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### Used Technologies
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### Used Technologies
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