docs: add plaintext option to README and skill

README.md

@@ -75,6 +75,9 @@ export POP_FROM="pop@charm.land"
 export POP_SIGNATURE="Sent with [Pop](https://github.com/charmbracelet/pop)!"
 ```
 
+Set `POP_PLAINTEXT=true` or pass `--plaintext` to send the body as plain text
+instead of rendering Markdown to HTML.
+
 > **Note**: If you wish to use a resend account without a custom domain, you can
 > use `onboarding@resend.dev` to send emails.
 

skill.md

@@ -39,6 +39,7 @@ Encryption options: starttls (default), ssl, none.
 
     POP_FROM          Default sender address
     POP_SIGNATURE     Signature appended to the email body
+    POP_PLAINTEXT     Set to "true" to send plain text instead of rendered HTML
     POP_UNSAFE_HTML   Set to "true" to allow unsafe HTML and extra markdown features
 
 ## Sending Email (Non-Interactive)
@@ -65,6 +66,7 @@ Body via flag:
     -a, --attach       Attach a file (repeatable)
     -x, --signature    Signature appended to body (env POP_SIGNATURE)
     -u, --unsafe       Allow unsafe HTML / extra markdown features (env POP_UNSAFE_HTML)
+        --plaintext    Send plain text instead of rendering Markdown to HTML
         --preview      Open the TUI to review before sending
 
 ### Attachments