The multiquote feature allows you to quickly quote one or more posts into either a new reply.
To select a post to be quoted, click on the https://community.mybb.com/images/english/postbit_multiquote.gif button below the post. The icon will change into https://community.mybb.com/images/english/postbit_multiquote_on.gif to indicate that the post has been selected. If you made a mistake, just click again on the button, and it will change back to the regular icon.
On the quick reply box, at the bottom will be the links "Quote these posts now" and "deselect them". Click on the "Quote these posts now" to add the selected posts to the message as quotations.
On a full reply, any selected posts will automatically be added as quotations.