You hit send on a launch email, and then the replies start arriving: the link is broken.
On the Pro plan, you can fix that URL after the Broadcast has gone out. Anyone who clicks from that point on goes to the corrected link, so you don't need to send a follow-up email.
How to change a URL in a sent Broadcast
Go to Broadcasts under the Send tab of the navigation and click the title of the Broadcast you want to edit. (Alternatively, click the View button next to the Broadcast.)
Select the Clicks tab. When the Clicks page loads, select the Edit option next to the URL you want to edit.
Edit the URL, then click Save to save your changes.
Subscribers who click after you save go straight to the corrected URL.
Note: Links containing liquid code, such as {{ affiliate_url }}, cannot be edited directly.