diff --git a/doc/advanced/config-cheat-sheet.en-us.md b/doc/advanced/config-cheat-sheet.en-us.md
index 1e97f93e..8ae89ef4 100644
--- a/doc/advanced/config-cheat-sheet.en-us.md
+++ b/doc/advanced/config-cheat-sheet.en-us.md
@@ -241,14 +241,15 @@ Values containing `#` or `;` must be quoted using `` ` `` or `"""`.
 - `PASSWD`: **\<empty\>**: Password of mailing user.  Use \`your password\` for quoting if you use special characters in the password.
 - `SKIP_VERIFY`: **\<empty\>**: Do not verify the self-signed certificates.
    - **Note:** Gitea only supports SMTP with STARTTLS.
+- `SUBJECT_PREFIX`: **\<empty\>**: Prefix to be placed before e-mail subject lines.
 - `MAILER_TYPE`: **smtp**: \[smtp, sendmail, dummy\]
    - **smtp** Use SMTP to send mail
    - **sendmail** Use the operating system's `sendmail` command instead of SMTP.
    This is common on linux systems.
    - **dummy** Send email messages to the log as a testing phase.
    - Note that enabling sendmail will ignore all other `mailer` settings except `ENABLED`,
-     `FROM` and `SENDMAIL_PATH`.
-   - Enabling dummy will ignore all settings except `ENABLED` and `FROM`.
+     `FROM`, `SUBJECT_PREFIX` and `SENDMAIL_PATH`.
+   - Enabling dummy will ignore all settings except `ENABLED`, `SUBJECT_PREFIX` and `FROM`.
 - `SENDMAIL_PATH`: **sendmail**: The location of sendmail on the operating system (can be
    command or full path).
 - ``IS_TLS_ENABLED`` :  **false** : Decide if SMTP connections should use TLS.