"\\b\\(attach\\|attachment\\|attached\\|anexo\\|anexado\\)\\b")
+## Avoid forgetting the subject
+
+It happens that we forget to enter the Subject line, particularly when
+we leave that to the end. It's easy to write a function that checks
+whether the Subject is empty, and add it to `message-send-hook` to get
+confirmation:
+
+ (defun my-notmuch-mua-empty-subject-check ()
+ "Request confirmation before sending a message with empty subject"
+ (when (and (null (message-field-value "Subject"))
+ (not (y-or-n-p "Subject is empty, send anyway? ")))
+ (error "Sending message cancelled: empty subject.")))
+ (add-hook 'message-send-hook 'my-notmuch-mua-empty-subject-check)
+
+
## Applying patches to git repositories
The `notmuch-extract-thread-patches` and