docs: improve login account options

default.nix

@@ -25,7 +25,6 @@ let
   inherit (lib)
     literalExpression
     literalMD
-    mkDefault
     mkEnableOption
     mkOption
     mkOptionType
@@ -145,8 +144,13 @@ in
             options = {
               name = mkOption {
                 type = types.str;
+                default = name;
                 example = "user1@example.com";
-                description = "Username";
+                readOnly = true;
+                internal = true;
+                description = ''
+                  The login username for this account.
+                '';
               };
 
               hashedPassword = mkOption {
@@ -154,24 +158,33 @@ in
                 default = null;
                 example = "$y$j9T$vfGrwkAaXCjCEWtVNMQck1$383uIXQmn2z0hnmVAA8kwFQmjNj78.nYbvWeyNLIaP1";
                 description = ''
-                  The user's hashed password. Use `mkpasswd` as follows
+                  The hashed login password for this account.
 
+                  Use `mkpasswd` to create password hashes:
                   ```
                   nix-shell -p mkpasswd --run 'mkpasswd -s'
                   ```
 
-                  Warning: this is stored in plaintext in the Nix store!
-                  Use {option}`mailserver.loginAccounts.<name>.hashedPasswordFile` instead.
+                  :::{note}
+                  This is a convenience option, when your threat model allows
+                  storing hashed secrets in the world-readable Nix store.
+
+                  Passing the hash through
+                  {option}`mailserver.loginAccounts.<name>.hashedPasswordFile`
+                  allows relying on filesystem discretionary access control as
+                  another security boundary.
+                  :::
                 '';
               };
 
               hashedPasswordFile = mkOption {
                 type = with types; nullOr path;
                 default = null;
-                example = "/run/keys/user1-passwordhash";
+                example = "/run/keys/user1-pw-hash";
                 description = ''
-                  A file containing the user's hashed password. Use `mkpasswd` as follows
+                  The hashed login password for this account read from a file.
 
+                  Use `mkpasswd to create password hashes:
                   ```
                   nix-shell -p mkpasswd --run 'mkpasswd -s'
                   ```
@@ -185,9 +198,13 @@ in
                     inStore = false;
                   });
                 default = null;
-                example = "/run/keys/user1-password";
+                example = "/run/keys/user1-pw";
                 description = ''
-                  A file containing the user's plain text password. The value will be hashed at runtime.
+                  The plaintext login password for this account read from a file.
+
+                  :::{note}
+                  The password is hashed before it is passed on to Dovecot.
+                  :::
                 '';
               };
 
@@ -199,9 +216,13 @@ in
                 ];
                 default = [ ];
                 description = ''
-                  A list of aliases of this login account.
-                  Note: Use list entries like "@example.com" to create a catchAll
-                  that allows sending from all email addresses in these domain.
+                  List of additional mail addresses (aliases) that get routed to this account.
+
+                  :::{admonition} Catch-all with sending permissions
+                  :class: tip
+                  Configure `@example.com` to create a catch-all for this domain
+                  that also allows sending from all addresses.
+                  :::
                 '';
               };
 
@@ -224,7 +245,12 @@ in
                 default = [ ];
                 description = ''
                   For which domains should this account act as a catch all?
-                  Note: Does not allow sending from all addresses of these domains.
+
+                  :::{warning}
+                  Does not allow sending from all addresses of these domains.
+                  Use {option}`mailserver.loginAccounts.<name>.aliases` if that
+                  is required.
+                  :::
                 '';
               };
 
@@ -266,9 +292,10 @@ in
                 default = false;
                 description = ''
                   Specifies if the account should be a send-only account.
-                  Emails sent to send-only accounts will be rejected from
-                  unauthorized senders with the `sendOnlyRejectMessage`
-                  stating the reason.
+
+                  Emails sent to send-only accounts will
+                  be rejected with the reason configured in
+                  {option}`mailserver.loginAccounts.<name>.sendOnlyRejectMessage`.
                 '';
               };
 
@@ -276,33 +303,38 @@ in
                 type = types.str;
                 default = "This account cannot receive emails.";
                 description = ''
-                  The message that will be returned to the sender when an email is
-                  sent to a send-only account. Only used if the account is marked
-                  as send-only.
+                  The message returned to the sender for a send-only account.
+
+                  See {option}`mailserver.loginAccounts.<name>.sendOnly`.
                 '';
               };
             };
-
-            config.name = mkDefault name;
           }
         )
       );
-      example = {
-        user1 = {
-          hashedPassword = "$y$j9T$y6eZ1o.IvVNfdGMAsUEvh1$6K/llP52uw2iDh4iSwtAn54/JYy7FzCcoCHmjmx00H5";
-        };
-        user2 = {
-          hashedPassword = "$y$j9T$hZ.ubq0M897Hw.znxnGG9.$14EJBoOwbwKeWt.W4vpnBPEBZC9mYz4fWI9kOCLoZf4";
-        };
-      };
+      example = lib.literalExpression ''
+        {
+          user1 = {
+            # This password hash leaks into the Nix store
+            hashedPassword = "$y$j9T$y6eZ1o.IvVNfdGMAsUEvh1$6K/llP52uw2iDh4iSwtAn54/JYy7FzCcoCHmjmx00H5";
+          };
+          user2 = {
+            # Hashed password passed as a file
+            hashedPasswordFile = "/run/keys/user2-pw-hash";
+          };
+          user3 = {
+            # Plaintext password file
+            passwordFile = "/run/keys/user3-pw";
+          };
+        }
+      '';
       description = ''
-        The login account of the domain. Every account is mapped to a unix user,
-        e.g. `user1@example.com`. To generate the passwords use `mkpasswd` as
-        follows
+        Attribute set of mail accounts.
 
-        ```
-        nix-shell -p mkpasswd --run 'mkpasswd -s'
-        ```
+        Each entry defines a mailbox and login credentials, where the attribute
+        name is used as the login username and optionally routed mail address.
+
+        Use `mkpasswd` to generate password hashes.
       '';
       default = { };
     };