diff --git a/doc/configuration.md b/doc/configuration.md
index aa73a0d..649b1d7 100644
--- a/doc/configuration.md
+++ b/doc/configuration.md
@@ -3,10 +3,10 @@ Configuration
 
 `.mailfull/config`
 
-| key | type | default | required | description |
-|:----|:-----|:--------|:---------|:------------|
-| dir_database | string | `"./etc"` | no | A relative path from repository dir (or a absolute path) |
-| dir_maildata | string | `"./domains"` | no | A relative path from repository dir (or a absolute path) |
-| username | string | The username who executed `mailfull init` | **yes** | It used for setting owner of database files and maildata files. |
-| cmd_postalias | string | `"postalias"` | no | Command name or path |
-| cmd_postmap | string | `"postmap"` | no | Command name or path |
+| key           | type   | default                                   | required | description                                                     |
+|:--------------|:-------|:------------------------------------------|:---------|:----------------------------------------------------------------|
+| dir_database  | string | `"./etc"`                                 | no       | A relative path from repository dir (or a absolute path)        |
+| dir_maildata  | string | `"./domains"`                             | no       | A relative path from repository dir (or a absolute path)        |
+| username      | string | The username who executed `mailfull init` | **yes**  | It used for setting owner of database files and maildata files. |
+| cmd_postalias | string | `"postalias"`                             | no       | Command name or path                                            |
+| cmd_postmap   | string | `"postmap"`                               | no       | Command name or path                                            |