Gmail Confirm Before Send

When the Send Mail button is pressed, a confirmation dialog box is displayed.
In the confirmation dialog, there are check boxes for sender (only when multiple email addresses are set), recipients, subject, and attachments.
When all check boxes are checked, the Send button will be enabled.
When the Send button is pressed, the system waits for a certain period of time before starting to send the message. The number of seconds to wait can be optionally changed.

There is also an option to disable autocomplete when composing an email in Gmail.
You can choose to disable autocomplete completely or another domains.
The default is to disable it for another domains.